I laughed at the idea of buying a cheap van, but yes, or a cheap caravan? We got one for 100 quid once, and you could take out a lot of the interior furniture (tho not too much cos it stiffens it up and makes it towable) to make space to work in. as they usually have some kind of kitchen worktop anyway it should be ideal, more light inside than a van so you can see what you're doing and it might even come with a heater though you have to be careful with heaters and fine sawdust in enclosed spaces, it can be explosive.