Sumps-
All qualifications help.
You have to decide what area you want to work in and then do the relavent exams.
If you want to be in maintenance then it has to be the licence route.
With a degree design and manufacture is probably more suited.
As for pay, I work for an airline in the midlands. An unlicenced fitter will be on 16 to 18k before shift pay, a licenced engineer 25 to34k depending on approvals.
I think that these are about normal away from the S.E. of england.