Out of interest, why did you quit?
I imagine it would be difficult to go back and get O/A levels at some point in the future, so this seems to be throwing away a great opportunity.
I appreciate it is easier to learn something that holds your interest, hence a JAA syllabus might be easier than an A-level English course, but you are leaving college missing an important and usefull polishing of education.
Should airline work fall through, what backup do you have? The techinical and professional nature of flight-deck work (one of the main incentives for getting there I think) will be hard to recreate in other employment if you don't even have the grades to attempt university.
Best of luck in your choice, but I think it would be worth considering there is a whole world outside of aviation that you are shutting off by doing this.
While A-levels seem to have been of little importance to airlines, they appear to be becoming more of a factor now (I'm no expert on this). You may well find showing a committment to finish education is viewed as highly as any number of hours you hold.