its a very interesting question, one that most of us have thought about more than once i'm sure, i think that it is possible, difficult and lonely, but possible, our modern world will hinder the free spirited just because thats how large societies work, they are trying to box us, as thats the best way to control us, and in societies you need control of your population, the alternative would be anarchy.
i work with animals, specifically dogs, and a good way to look at it is this, would you take your little pet and throw him out in the wild alone and expect him to live as a wild animal? survive maybe but live? some breeds would have more luck than other as some more resourceful humans would, but we have been domesticated just like out pets so most would just survive and not really live.
in the uk tho do we sill have the space and the clean enviroment that could sustain a healthy life? it would depend on weather you can find that enviroment in the uk i think. not an easy task.
but i wish you all the luck in the world.
paul