Amazon.com have Battlefield 1 for Xbox One for $30 works out about £24.50, want to save more consider Xbox game share with a friend.
As per usual UK bank will likely charge a foreign transaction fee, HSBC charge 2.75% fee, Natwest I believe will charge you £1 plus a % for info.
Just add a USA address simple...
For reference £31.34 at cdkeys.com after 5% facebook like.
Premium Edition download around £41 also ($49.99) see here
PS4 download also available for $30 however for American PSN accounts only.