I found this website today, it looks good & they ship to the UK (with reasonable shipping costs, up to 4 yards of fabric for under $12.00). I have been buying from the US but the bigger sites have increased their shipping costs recently. I know it is expensive to ship things but sometimes they just overprice the shipping to put international buyers off I'm sure! Some have a set shipping price of $30 - $40 dollars which is fine if you want lots of fabric but no good if you only require a couple of yards. However, I am not complaining because the choice is fantastic compared to the UK and it is usually half the price for the fabric in the first place, so this balances out the shipping.
Another site I found was isew which is UK based. At last something about sewing that is up-to-date and based in the UK! I will be joining the forum later. Lots of ideas & tips. Great.