I have three good A levels, with good results, not involving maths or a traditional science. I did double science at GCSE and again, got a good mark. Maths GCSE was above average but not outstanding. I have a PPL and night rating.
I wouldn't get too hooked up on grades and flying hours. If you have the minimum required, you have just as much chance as anyone else. Yes, you'll have to prove yourself in the interview and team building exercises, perhaps more than the "educated" counterparts in attendance.
Remember that CTC are rating you on suitability and risk. If you present a low risk to them as an organisation then you can pass. If you present a high risk, you won't. The areas in which that risk lies will vary from person to person. It's up to you to analyse your weaknesses (i.e. the potential risk) and turn them into strengths to prove you have what it takes.
They aren't dumb. They know that sat in the RHS of an airliner, the shape of the ink printed on your education certificate matters relatively little.
I passed so far....bar one of the team building exercises that went belly up. Re-invited back this summer.