do NOT go back to doing A Levels now. Unless you're planning on going to uni, they won't help you diddly squat. In two years you'll be eligible for mature learning at uni anyway should you need it, so what's the point? Airlines don't care. What a waste of time when, as people say, you should be working and saving hard. Sounds good to an interviewer as well.
that's only my exp though, and I don't even have gcses, so excuse the bias!
why anyone would be suggesting for this guy to do a uni/college degree now is beyond me, he's already told us that every penny in his life must be earnt before it's spent, why go down a road of piling on more debt? don't go, take the sting out of the tail somewhat and do what you love. I did and it worked.