Not lifestyle for me, but it is likely not actually that different from possible rents in any bigger cities. So it might work for year or two. And after that, just get a real place.
"technically has no fixed abode" I think here probably actually means he's registered at his parents house. This would likely be a lot more difficult if you were truly homeless.
For exchange of no fixed location, and just a single tiny sleep room, though.
I'd be willing to bet that even a regular home (unit/flat/apartment/small house/whatever) can likely be rented for 1/5th of London rental rates, if you look in the right places: i.e., not in major cities.
Cities are expensive; Being able to work from "anywhere" makes it quite easy to make your money go a lot further, particularly in terms of housing, without resorting to being a glorified homeless drifter.
The article says he often eats (for free) at the 1st class lounges at the train stations