Tandy is opening up more and more shops in the US again. While I have seen some really nice leather online, I'm with Donnie in that I'd much rather see the leather in person (sometimes it can be split or skivved wrong, have unsightly markings, etc.) A lot of Tandy's leather is imported, but at least I can pick through everything and find the best stuff. Like any natural material, each piece is a little different. And if you can find one of the former "Leather Factory" stores that Tandy bought, they're MUCH larger than most of Tandy's other stores.

Also, take advantage of their remnants bins...sometimes you can find some really good stuff in them for pennies on the dollar (or pound, in your case.) There are some excellent and well-respected leather dealers online that probably have slightly higher quality leather in some cases, but I'd rather pick it out myself and not have to hassle with ordering sight-unseen and waiting for it to arrive.