I used to be scared of homeless people and I used to give beggars money. I was wrong on both counts.

A cold, wet, January night in the streets and deserted parks of south-west London looking for rough sleepers is more than enough to dispel any notion I once had that homelessness is a lifestyle choice. It is not.

It is miserable, so miserable that one homeless man outside Clapham Junction station quietly said: "Can you help me? It’s horrible living out here."

Following two recent high-profile homeless cases the Wandsworth Guardian decided to spend the night with charity Thames Reach searching for rough sleepers, getting them help and short-term accommodation so they do not spend more than two nights on the streets.

You might argue this is a load of self-righteous rubbish I compiled from my warm flat, while listening to the gale force winds outside, and you have a point.

But there is a story to be told. Homelessness is not just sleeping bags, cardboard and doorways; it is mental health, super-strength lager and eastern Europeans living in tents.

Most of the time hostels are full and there are serious gaps in the system being plugged by charities on the frontline.

My night started by meeting some of the Thames Reach team in their Stockwell office, where they filled me in on homelessness in south London.

Alcohol, namely super-strength lager, I am told is the biggest problem among Wandsworth’s rough sleepers and about a third of its homeless are from eastern or central Europe.

The charity even has a wall where they note the number of homeless people they have helped return, in dignity, to their country of origin.

Wandsworth and Merton have "hot spots" where foreign nationals, usually from eastern and central Europe, gather. Thames Reach employs foreign speakers to interact with them.

But rough sleeping is also about people who have fallen out of the system and have very complex needs.

One worker tells me about a fragile homeless man, with mental health problems, who has been sleeping under a bush since December 3. The only appointment he can get with mental health services is on January 16. Even then, there is no guarantee he will attend.

Rob Twisse, my guide for the night and a lead worker for the charity’s London Street Rescue team, has been working with people on the streets for 15 years. He has only been threatened once in all those years.

The team tell me there is a difference between homelessness and begging, although the two can go hand-in-hand.

Heroin and crack addictions fuel begging and although Thames Reach supports beggars it advises people not to give them money because it only lines the pockets of local dealers.

Wandsworth Guardian: Heroin

Giving to beggars only lines the pockets of local dealers, I was told 

Often people begging are housed and the money you give them could pay for the hit that kills them. More homeless people are dying of super-strength lager than drugs, I was told.

We head out, just after 8pm, to start searching for people who have been referred to the team by national call service Streetlink, through which the public can report rough sleepers.

I am told all the local hostels are full for the night and boroughs rarely take rough sleepers from outside their area.

We started searching Mitcham Common by torchlight for a tent of eastern European men. It is groups such as this who queue up at building yards looking for work, often paid well below minimum wage.

We scour high and low among the scrub for a tent, trying to find a needle in a haystack, but the group appears to have moved on. On to our next referral, a male and female couple, in a quiet Wandsworth suburb. The woman was described as an anaemic heroin and crack user.

The referral says they have bedded down in an alleyway but again, no luck, there was not a sign of them.

Rob speaks about how unlikely it was to meet servicemen on the streets and says he would cheer if he met one because there is so much out there for them in terms of support.

We hit the streets around Clapham Junction following concerns about a woman sleeping rough.

Wandsworth Guardian:

There we find a body tightly wrapped in a sleeping bag. After gently trying to wake them up on bended knee, a woman did not emerge; a man tells us he just got out of prison and he was rather unhappy we had woken him from his sleep.

On we plod and we meet one man, Stephen, in his 40s outside the station with his dog. He says: "Can you help me? It’s horrible living out here."

Still raining, we all get down on our knees to talk to him. He tells me how he had been sleeping rough nearby since April 2013 when he lost his home and had family problems. He had lived in Battersea most of his life.

He says: "It is hard. My legs ache, my whole body aches where I haven’t slept properly. I just want a place to live, to stay. To get my life back."

He makes about £40 a day begging and spends £30 a day on heroin. He tells me: “I didn’t used to take it. I used to work as a labourer. When I lost my daughter I started taking heroin.

"I lost my little girl, and my mum just before. I was never in to heroin before that. My daughter was three months old. She just died. I was really happy when she was born."

He tells me stories of being bullied on the streets and assaulted by strangers, adding: "I was dragged along in my sleeping bag and smashed over the head with a ‘for sale’ sign."

It turns out Stephen is known to Thames Reach and they had contact with him a year ago. Rob takes down all his details and asks if he would like a birth certificate – just one small step back into society. The team buys him a burger and food for his dog and we are off to our next referral.

As we weaved from one referral to another I asked Rob about some of the worst cases he had seen. He told me of an “old boy” living in an alleyway in his own faeces surrounded by rats and another man who had such a badly wounded leg it was infested with maggots.

We talked about the problems of super-strength lagers, alcohol addiction and how some people’s addiction was so severe it led them to drink alcohol-based hand gel dispensers from hospitals.

Rob also tells me about one person who died on the street in Lambeth from hypothermia. Since then there have been changes, services linked up and efforts made to get people in touch with mental health workers quicker.

Then there was the young man living in a tent hidden away for 10 years. He would only emerge to rummage around bins and had not had a change of clothes in a decade. He was eventually sectioned and is now doing really well, is housed and comes back to help the team.

"That wasn’t a lifestyle choice, he was clearly ill," says Rob.

"Nobody wakes up in the morning and says I’m going to sleep on the streets. It’s a gradual thing – people lose their jobs and houses – it’s a slope."

But rough sleeping does not have to be a horror story. The charity has helped thousands of people get their lives back on track. Rob told me about one particular event that stood out to him: “I was on the Tube one day when a formally dressed young man tapped me on the shoulder and gave me a hug. I’d met him on the streets and now he was in his second year of uni.”

We scour a usually busy area in Wandsworth Town but find no sign of a man who has been sleeping rough locally and is known to lash out.

Tooting Common is our last stop, a place only frequented in the early hours of the morning by those seeking a “dogging” hotspot, so I have heard. Again we have no luck finding our final homeless man and I am told this can happen, particularly on wet nights.

Despite not finding any of our referrals we had success with Stephen, with enquiries now being made to find out his story and get a roof over his head.

Wandsworth Guardian:

Rough sleepers are not benefit scroungers, it is impossible to claim benefits when you have fallen out of society. Rough sleeping is not just about getting a roof over people’s heads; most face a battle with alcohol and mental health problems.

It is also not as simple as getting them mental health help, because visiting your GP is only possible if you have one. It almost goes without saying that a housed person gets better healthcare, quicker, than someone homeless.

Once you are on the streets the more you will deteriorate. You are exposed to assault, people using drugs and super-strength lagers.

If I can take anything from this experience it is to make an effort to speak to rough sleepers instead of looking the other way and, if they want, to buy them food.

Having heard how much a beggar's money is spent on their drug habit I will never again add to the perpetual cycle of addiction by giving cash.

If you have concerns about someone sleeping rough, call London Street Rescue’s streetlink number 0300 5000914.

To donate to Thames Reach visit thamesreach.org.uk/help-us/donate.