G-BPEC,
probably best to look at this in a couple of different ways.
First off, i did A level physics not so long ago, and it can be a hard old slog if you aren't really into it. As with any A level, have a look at who'll be teaching it as this can make a big difference as to how you'll get along.
Second, if you're thinking of going to uni before flying, choose very carefully because a bad choice now will preclude you from many courses, i.e. no physics means no aerospace/engineering/science. . .There's been much debate on this forum on the merits of getting a degree first. My take, for what its worth, is that it is better, especially if, like you and I, there might be class 1 concerns lurking about. Having said that, my good pal Tunneler took the plunge sans degree and isn't having too many regrets.
Mentioning a modern language is probably a good idea, and will stand you in good stead whatever you do,and I would always advise A level maths whatever else you choose.
On a final note, you might be able (depending on your school/college) to choose 4 A levels and if the workload or material in Physics really isn't for you, it can be dropped before you get in too deep. I know its not an ideal solution, but it has worked for people I know in the past.
What people say here will just give you things to think about, in the end discuss it with teachers, careers tutors, folks and friends. And make sure its your decision.
Best of luck in whatever you choose,
Regards,. .BGPM.
ps for the record I did Maths, Physics and English Literature, got ABB and a lasting hatred for Jane Austen.