Funnily enough, I was thinking of posting more or less the same request, although I'm willing to entertain looking at online sites as well, so long as I wouldn't be spending stupid amounts.
On the Zombocalypse ride I had a serrated kitchen knife, which was fine to use, but somewhat lethal in my camping kit, so it had to be wrapped up pretty thoroughly to avoid it putting a hole in something important, like me! Certainly for my purposes folding would be a damned good idea, legal as well obviously, although that should go without saying for shops in the UK.
I'm not 100% sure of the law, I think it's OK so long as it has less than 3" of blade, and isn't a gravity knife or flick knife? It'll live with most of my camping kit anyway, so isn't likely to be on my person unless I'm actually using it for something dangerous like cutting bread.