The grades themselves aren't the most crucial things, someone with the minimum requirements has the requirements and can go on from there.
However, and this will be blunt, you don't.
You need to have C or above at GCSE and you have to have at least 2 A Levels.
Seeing as you don't have a degree either, you don't really have a leg to stand on to ask for a review at an AFCO.
If you want in, your only route is to correct those D grades at GCSE in English (unless your C was in English Language) and Maths and make sure you've got 3 other GCSEs at C or above, AND then get yourself 2 A Levels.
After all that's happened, I would be wary of the age limits too, as you'd be getting very close to them already, despite all the extra work you will need to do.
Frankly, if you wanted to be a pilot in the RAF, why didn't you find out what was required for such a position, rather than go off on your own steam down a route that was basically useless?
Anyway, to answer your question:
"Just because i don't have As and Bs in GCSE's will i just be completely over looked?"
Basically, yes. Not because of the lack of As and Bs, but the lack of enough of anything.
Because of that, the other questions are largely irrelevant.