Crankcase,
I think in your case doing well in ATPL theory is what you should set as a goal.
Forget about those A-Level results, and the perceived disparity between crap D results and this 132IQ thing.
I got tested at when at Uni, scored 128. Got tested recently, knowing that my mental functioning has certainly deteriorated to, oh, about the level of a village idiot, and I scored 130.
I know that can't be quite right. No nice way to say this but you have to face up to it:
You ****ed your A levels. That in turn has seriously affected initial impressions of people in recruitment, who have the paper bin sitting hungrily by their side.
You are obviously bright enough. I get the impression from reading this thread that the critical factor is motivation.
If you keep yourself highly motivated, chances are you will put the effort in and perform as you know you can.
Best of luck with the ATPL's.
JH