I know several people operating wide body airliners for some of the biggest european flag carriers, with no GCSE's.
This is not to say that they are not important, good knowledge of Maths, Physics and English are key to passing the ATPL exams. I would take the exams if you are able to.
As for weeding out your application if you don't have high school exam results ticking certain boxes, not sure I believe that one.