This sounds like a brillaint idea, I would definately be interested if this thing went forward.
I think though if it were to go ahead, even though it is important for it to be done all legally and fairly, use of it should not be limited to 'if you paid £2000, you get to use it more than the guy who only paid £500'. I think it should be a 'you paid some towards it, you can use it as much as the next guy (as long as you're responsible, respectful and careful').
I think also, the main reason for group buying a piece of land, besides the fantastic perk of being able to share some bushcrafting land, should be to have the privilage of looking after some beautiful wildland for the next generation. And to remember that it's not 'ours to do with as we please', but 'our responsibility'.
Just my thoughts,
Dan