My biggest piece of advice for you would be to slow down and get your A-Levels finished.
When I was your age I thought I'd join the RAF as a fast jet pilot if not, I'd be an airline pilot.
Now I'm older, I've been to University I've worked a few jobs I've realised I was extremely naive and far too excited about my dreams. You need to slow down and get your A-Levels out the way and take it step by step.
Right now, it's hard to get a job! I work with a huge company where we have qualified lawyers, accountants and a number of other professions working in a call centre because there is nothing else out there.
If you decide to go to University do something you're actually good at and not what you think the airline will like. There is nothing worst leaving University with a 3:1 degree in engineering when you could get a 1:1 in Business for example.