There was a recent thread about this (but I can't find it right now

) - 'fully' flexible, 'fully' refundable tix (on BA at least) apparantly suffer a fee (from £15) to cancel. This is what AskBA has to say:
http://generic-uk-questions.custhelp...cGFnZT0z&p_li=
so a £15 fee at least if it's just for you...but £15 or even £30 may be worth it if it significantly helps your plans though - only you know that
Good luck!
Phil