Passed the ATPL's with no A-Levels and just 4 GCSE above C grades. Not heard of any employers delving into your pass rate for ATPL's but they are likely to ask if you passed your IR first time.
As has been said, the ATPL's are all about dedication in wading through the quantity of work. Worrying about a scientific or mathematic background is pretty pointless from a self-sponsored perspective because I never even passed those subjects at GCSE level let alone degree level however, managed the ATPL's! Probably because I screwed around at school but I digress as always.....
Choosing the correct school is the key. I would vote Bristol Groundschool without a moments hesitation. Best advice I could possibly give anyone to be honest.
VFE.