This thread indicates that the fuel surcharge is non-refundable (on a non-flex ticket). However, BA Ts & Cs seems to indicate that they are:
4b4)If you do not use your ticket, you will be entitled to claim a refund of any taxes, fees and charges which you paid, less a reasonable service charge.
I have a booking with 'Tax/Fee/Charge GBP 50.30', so it would seem clear to me that this is the same 'taxes, fees and charges' which are covered by 4b4). Am I going to get this back automatically, or am I going to have to take BA to the small claims court