Never knew they moved the @-symbol in the uk!? Or do you mean it's in a different place in the UK than it is in the US?
Anyhoo, I live in Denmark, and I get the choice of different keyboard layouts/os combos when I order. Shouldn't you be able to do the same over there?
Here's a link (hoping it will still work):
http://store.apple.com/Apple/WebObjects/dkstore.woa/9374043/wo/4p43FlUhkxoK2vVKvJZXNvW65PU/2.?p=0
Edit: a closer look reveals that you can get "intl. english" here, not the american version. However, the american version has one key less than the "intl. english"/danish/swedish/german/austrian/younameit.
Hell, why not remove all of your keys and go with a dvorak-layout instead?