There used to be one, but now the HP geniuses have www.usairways.co.uk just redirect to www2.usairways.com/awa/ (and same with www.usairways.fr, www.usairways.de, and so on). They also got rid of www.usairwayscargo.com, and that just redirects to the main site too.
Don't worry, though, I'm sure Barbell will be on shortly to tell you that the website always works perfectly, and that you're the one with the problem.
(Seriously, if you're intent on flying US, you'll have to call UK res at 0-845-600-3300, or just book on a third-party site like Expedia.)