Andy Strangeway lives, eats and sleeps Scottish islands. Two years ago he became the only person to have spent the night on all 162 islands of over 40 hectares and now he has his sights set on the big one – or rather the little one, Rockall. With a perimeter of just 25 metres and standing 23 metres high, Rockall is more of a rock than an island and, 229 miles west of North Uist in the Outer Hebrides, it's also the most difficult island in the world to sleep on.

To Andy's knowledge only four people have achieved the feat but none of them were from Yorkshire and none did so, as he plans to, without shelter. Not even, he maintains, Tom McLean who most famously resided on Rockall for 40 days back in 1985 to affirm the UK's claim to sovereignty over the islet. Andy, 44, came within a few metres of his goal in May last year after a 20-hour crossing from St Kilda, Britain's most far flung inhabited island. "Our original plan had been to take a tender alongside the rock and jump out but we'd no chance of doing this," he said. "But one passenger had brought with him a wet suit which was a stroke of pure luck. This meant that landings could be achieved by swimming into the 20ft swell, being thrown onto the rock and holding onto kelp before scrambling on in advance of the next wave.

"Using this method, three of us managed to get to the top of Rockall and three others were able to land for between one and 20 minutes. Unfortunately I was not among them. I'm not a strong swimmer and we were out of the rescue zone so I declined an attempted landing.

"The first time I went out I was totally naïve. I didn't know what I was talking about and I was with the wrong people. I now know how to do it. I've got the best team I've ever assembled – a skipper, marine engineer and two climbers."

All he needs now is three months notice to get everyone on standby, a three-week window to make the actual trip (ideally in May or June) and the small matter of a yacht.

"I've got three possibles available for 2010, two of them charter boats and the other is a boat owned by a friend of mine who can definitely take me out there. As for 2009? Well, you never know. I live in hope that I will find someone who wants to come and have a bit of an adventure with their own yacht."

A rival could ultimately steal Andy's thunder – or provide him with unwelcome overnight company. Mountaineer and scuba diver Nick Hancock is planning to spend a record-breaking 60 days solo on Rockall in aid of the Help for Heroes charity to coincide with the bicentenary of the first landing on the island by the Royal Navy in July 1811. To make the threat all the more serious, Hancock is a Lancastrian.

Andy's fascination with Scottish islands – he calls himself an "islomaniac" and "daft tourist" – was triggered by buying a copy of Hamish Haswell-Smith's definitive guide to them while on holiday in Dunoon, a peninsula in the Firth of Clyde. But not content with fleeting visits he set off to sleep on every island in what he has since dubbed "Strangeway bagging", a Strangeway being a Scottish island you've slept on.

Over a period of four years from September 2003, he made a total of 18 trips to Scotland of up to five weeks from his home near Stamford Bridge, initially by train but later mainly by car which often doubled up as accommodation.

Being a vegan for the early trips added an extra challenge of avoiding an all-chip diet. Most of the arrangements were based around ferry timetables and boatmen contacts with little use of the web other than for the sending of occasional emails. Gaining permission to sleep on some islands was a headache in itself (especially for those protected for environmental reasons) and was sometimes only granted because it would be a first. Andy soon became an expert on the Scottish Outdoor Access Code.

"Being personable and a decent lad goes a long way to getting to these islands," he said. "You've got to build up the boatmen's confidence in who they're dealing with by starting with the easy to get to islands and working your way up."

He grew to have confidence in the boatmen too despite their erratic ways and also benefited in his quest from the self-helping ethos of Scottish island communities. Andy's job is self-employed interior painter and decorator, so it was relatively easy to arrange his life to fit in with his travels although they have left him with a large overdraft, some of the charters for the very distant islands costing four-figure sums.

"Sherpa Tensings", as he calls them, do not come cheap. Andy was familiar with working for long periods then travelling for long periods from his youth when he spent many winters in India, developing an interest in Buddhism. Today he visits the Madhyamaka Buddhist Centre in Kilnwick Percy near his home. Being alone on a Scottish island is often tantamount to a spiritual experience which is partly how he explains their lure – and may also explain why psychic Uri Geller has has bought Lamb Island, one of three rocky outcrops in the Firth of Forth which mirror the layout of the pyramids at Giza.

Within days of the purchase being announced in February Andy had contacted the new owner and made the Lamb the 89th island he's slept on alone. "I never understand why people would be frightened being on their own on an island," he said. "If I get lost going through the centre of Glasgow and come off the M8 then I'm frightened. I'm very happy with my own company. I never get lonely. I fully enjoy solitude. Nobody ever got enlightened at the local Hilton. On your own you become one with the island. I always believed that the islands would allow me spend a night on them. I never doubted that."

"Andy is almost monastic at times," adds his wife, Ruth, who has chalked up six Strangeways. "He loves to be in that compact unit of his tent. It gives him that monk's cell sort of feeling. Sitting on a rock watching the sea is very contemplative." But how does she feel about being apart for long periods?

"It was quite difficult initially as he was away weeks at a time and I was working and running everything at home and missing him. In the early days when he was doing the scheduled ferry islands I wasn't so concerned but when it started to get more difficult I was really anxious to know how he was, particularly when he was doing those last ones around St Kilda. But you get into a routine. My job's so challenging and I'm away a lot at the same time as Andy and we just got into it."

Despite Ruth's fears, Andy has never been marooned on an island because of the weather although his tent was lifted off the ground in a force 11 gale – "like being in a continuous car crash" – on Gairsay. "The weather's not as unpredictable as you think," he said. "It's very rare for something to change quickly overnight. You know it's coming in. It won't just appear. What I'd love to do, though, is to pitch up on one of these islands for two or three months of winter." But that challenge will have to wait a while. There's Rockall to be conquered first.