Wow, with that much money you could buy something much bigger. My suggestion, get a cooler, a big one (those are only like 20-30 quid, right). Then with the rest, I'd buy a nice box of cuban cigars

A desktop humidor is nice, but never more than 30-50 american should be spent on one just because their capacity sucks. A cooler is airtight, keeps consistent temperature and costs little. Put some beads in and you're set.