Don't be intimidated by mathematics as a subject. It's really only a language that enables you to understand the fundamental aspects of the real world. Unfortunately it is often presented by rather uninspiring people!
Like Oldie Volvo I've got a less than perfect academic career but have served out some time in the RAF and now fly for an airline. The RAF gave me a lot of confidence with maths because the training that I received related to problems faced in the real world and you could see first hand why such knowledge is so valuable.
That said, at your stage in the game I found maths to be rather intimidating and certainly dull. Do remember that there is always a hard way and an easy way of doing things. If you can produce the goods at
A Level you stand more chance of convincing an airline to pay for your training: more importantly you will have a job at the end of it.
A real tip for passing exams is to get hold of the syllabus and work through each point on the list crossing them off as you go. If you know your stuff on each point you will not get any nasty surprises in the exam (if it aint on the list they can't ask you!).
Good luck - never mistake effort for progress.