Assuming you only have a UK address, this thread below will be most of value to you as far as CC offers. CC bonus offers don't tend to be nearly as generous in the UK and Europe. You mentioned 2 tickets - if you have a spouse or significant other that could apply for card(s) simultaneously that would help, of course.

http://www.flyertalk.com/forum/miles...er-thread.html

This will inform your decision as to the best FF program along with the data that sbm12provided on redemption rates.

Just thought to add that Starwood AMEX does have an offer in the UK, though the 20K bonus in the above thread may not still be active (10K standard). However the recommendation to look at USAirways is good, and if you can get 20K Starwood points, that would transfer into 25K US miles, which would help.