I wasn't sure, but I thought that I had heard that the availability was a bit different over there. That is why I decided to post the link.
This site does have a relatively strong contingent of UK hobbyists/breeders, though I am not sure whether any live close enough to you to give you any good recommendations. I believe that in the thread that I linked there was mention of the price of grain rising, which effected the availability of lab mice (leading to a bit of a price increase).
Again, good luck.