Part of the issue is that for science courses at university most will have some GCSE Maths requirement. It will vary but it is something you need to be aware of.
Here is an example for Chemistry at Bath
GCSE requirements:
GCSE Mathematics grade 6 or B
GCSE English Language or Literature grade 4 or C (or equivalent from English language category C)
You do not need the required grade in Mathematics if you study a higher level qualification in Mathematics (such as an A level, AS level or a Core Mathematics qualification).