It's not unusual to come up with a challenge to make life a bit more interesting as we reach the beginning of middle age, but Bristol's Jonathon Bradshaw has decided to push the word challenge to its furthest limits – he's decided to swim the Atlantic.

The fact that only one other man in history has ever tackled the 3,600-mile feat, doesn't seem to be putting him off.

All this would be remarkable enough, but Jonathon only learnt to swim in 2005.

The whole thing might be difficult to believe, except the 38-year-old has been doing lots of unusual things in the past few years.

It all began back in 2007, when he had a dramatic "Reggie Perrin" moment.

"I'd been running my own computer software business in London for 13 years," says Jonathon, as he leads the way into the lounge of his Clifton apartment.

"I'd had great success with the company over the years, but by the beginning of 2007 I was having problems both in work and at home – my marriage had collapsed, and I suppose I just had a breakdown.

"On February 23, 2007, I decided on the spur of the moment that I needed to change my entire life – there and then.

"So I packed in work, got rid of the business, sold my house – in fact, I sold all my worldly possessions, everything except for my bike and a few of my clothes. It was a clear-out, on a massive scale, and it was incredibly liberating.

"Then I got on to my bike, and started cycling. I remembered that when I was young I'd had dreams of visiting places like Greenland and Iceland, so I cycled north.

"When I reached the north of Scotland I caught a ferry to the Shetlands, cycled across the islands, and then caught another boat that took me to the Faroe Islands. From there I continued on to the east coast of Iceland.

"I cycled across the whole of Iceland, through the inhospitable wilderness in the centre of the island, and finally reached the west coast and Reykjavik.

"I started to realise that I was having the time of my life. Just me and the bike. I had all those years of working in an office, all that pressure and misery to get out of my system. So I decided to keep going.

"I caught a ship to Greenland, and asked the Danish authorities if it would be okay if I cycled across their country. They laughed at me, and said I'd struggle to get across the country on skis, let alone on a bicycle.

"But they put me in touch with an expedition that was planning to cross the frozen wastes of Greenland just three weeks later. I met them, and they were so impressed with the fact that I cycled from London, that they agreed to let me join them."

Jonathon, who was brought up in Wick and educated at Colston Preparatory School and St Brendan's College in Brislington, discovered a new passion for adventure as he crossed the inhospitable icy tundra of the country.

He says: "I realised I loved Arctic skiing, and when I met a group of polar explorers who were out in Greenland training for a trip to the South Pole, I begged them to take me with them. Remarkably enough, they agreed.

"I completed my journey to the other side of Greenland, and then had just six weeks to try to put on some of the two stone in weight I'd lost, and prepare myself physically and mentally for an Antarctic expedition."

It took the team 58 days to walk from the sea to the South Pole.

"It was the most amazing experience of my life," Jonathon says. "And as I reached the end of the trek, I started to think, what on earth am I going to do next? I realised I loved the life of an adventurer, and I wasn't about to go back to an office.

"I wanted to do something that hardly anyone had attempted before, and something that genuinely terrified me. So I thought, I hate swimming – I only learnt to swim in 2005 – so why not try to swim the Atlantic?"

Jonathon moved back to his native Bristol, and began to make a living out of after-dinner speaking and leading corporate motivational events.

"I started to plan the swim across the Atlantic, and I also decided to start giving free talks to schools across the country about the importance of keeping fit so that you can live your dreams."

As we chat, Jonathon is surrounded by maps and charts. The bookcase which fills one whole side of the room is packed with titles about travel and adventure. The Indiana Jones trilogy DVD sits beside the TV set.

"When I was at school I was the bullied little fat boy," he explains, looking out of the window for a moment, before returning his thoughts back to room.

"I want to help kids get out of that situation, or even better, develop a love for the outdoors that will lead to plenty of exercise, and stop them from getting into that situation in the first place.

"That's why I'm not going to just swim the Atlantic for my own ego. I'm going to do it with a hundred thousand school children."

The idea is simple enough. Jonathon hopes to get thousands of schools on board across the country. Their children will follow his progress in geography lessons via video diary updates on his website.

He explains: "Each child will also try to get £10 sponsorship to swim a mile with me. Of course, they'll be doing it in swimming pools, but if we can get 100,000 kids on board, that will be £1 million that we can donate to charities that work towards inspiring children to live a more active and outdoor life."

In the meantime, there's the small issue of swimming the 3,600 miles across the Atlantic to sort out.

"The plan is to do the swim in the summer of 2010, during the short weather window that the summer months provide. I have a yacht lined up with a skipper," he says. "I'll swim from New York to London, following the Gulf Stream, which will give me a real boost.

"In fact, if I was laying still on a lilo, the Gulf Stream would get me back to London if I waited long enough.

"The yacht will drift ahead of me on the Gulf Stream, towing a sailing anchor to slow it down to my swimming pace. I will lay on top of the anchor swimming along.

"I've sorted out every little detail – even down to the shark resistant wet suit I'll need to wear during the swim."

It will take three months. Jonathon will swim for six to 10 hours each day, before climbing back on to the yacht to eat and sleep. During the night the boat will be allowed to continue drifting across the ocean, but only at the pace of the Gulf Stream.

"I think that's reasonable enough," he says. "After all, when people row across the Atlantic, they don't stop the boat from drifting through the night."

Jonathon has already started a relatively gentle preparation regime – swimming at the Clifton Lido and Clifton College swimming pool four times each week for a couple of hours per session.

The only thing standing in Jonathon's way now is cash. He needs to find sponsorship to pay for the expedition, which he estimates will cost £350,000.

He says: "I've tried every big local business you can imagine, but it's a difficult time for the economy, and it's not the best time to ask for major sponsorship for an event like this.

"But £350,000 isn't a massive amount of money for a big company, or even a group of medium-sized companies. I just hope somebody will come forward to help me get out there and do this thing that seems impossible when you first say it, but when you sit down and plan it, is actually achievable."

It has only ever been attempted once before – Frenchman Benoit Lecomte managed to swim the Atlantic in 1998, however American athlete Jennifer Figge managed to successfully tackle the significantly shorter journey across the mid-Atlantic earlier this year.

"It is possible," says Jonathon with a fixed stare. "The challenge will be 90 per cent mental and 10 per cent physical. All I want is the chance to give it a go."

To find out more about Jonathon's challange click here.