If its for plastering you will have to rule out the smaller vans like berlingos or swb connects because you wont be able to get the 8x4 sheets in .....if i remember right the lwb connect is the smallest van you will be able to get them in......used to have a yard full of vans years ago you could of virtually helped yourself but its a Mcdonalds now
My boss has the merc vito cracking van but out of my price range, Size isn't to important as 8x4's are usally bought in bulk and dropped off on site.
if thats the case buy a Caddy