concrete foundation not necessary for a shed, but you might want a nice level surface. My shed came with three bearers which you put underneath the base on a firm level surface; if your topsoil is firm enough, a 12in square slab at each corner & two across the middle should be good enough. Not sure if you'd need a fully slabbed surface though
whereabouts are you? There's a garden centre in Bradford with a decent range of sheds, and an 'outbuilding' supplier in Leeds that looks pretty good too. Does sheds, wendy houses, garages, greenhouses etc.
and **** me, look over there —->
there's an ad for gardenbuildings direct. How the f*** did that get there?
<edit> it's gone now </edit> but the prices looked quite good. 8×6 apex shed for under £200