I'd agree with the positive comments everyone has made - Warmoth make good quality stuff and a decent price and are very friendly and helpful.
I'd just reiterate what Philly said about factoring in the cost of VAT and import duty before actually purchasing. It was something I nearly didn't do when I ordered mine, as it was bloody hard to get figures for import duty. Ha d I not done, I'd have regretted it.
VAT is (as we all know) 17.5%, but import tax can vary. As a rough guide, work it out at 9%. That's what I did, thanks to a suggestion from Antag, and I was about £1.50 out. So you'll want to take your total Warmoth spend (excluding delivery charges, which thankfully they can't tax you on), convert it to £s and then add 26.5%.
Also make sure you have cash or a chequebook to hand when the stuff is delivered - you have to pay the import duty/VAT to the UPS guy, and they don't take cards (or at least didn't as of June last year).
Hope that helps/makes sense!