If you use my iherb
discount code JOJ321 you can get $5 or $10 off of your first order. Shipping to the UK is only $6 of you keep the weight under 4kg.
I just ordered some Clif bars and Nature's Path Chococonut bars. In the past I've ordered spinach linguini, Late July cookies, Edward & Sons Not Chicken/Not Beef stock cubes, Hurraw & Crazy Rumors lip balms, brown rice marshmallow treats & Chocolove bars (the almond & sea salt is SO good). They used to sell Dandies and Eco Planet cheddar crackers, I need to email them again to see when they'll be back in stock.
The only thing to be careful of is the customs charges on vitamins & supplements. They're light so the shipping's cheap but the customs charges can be epic.