Further maths or computer science a level?

So far I've chosen biology, physics and maths but I'm not really sure about further maths and computer science. The sixth form doesn't offer further maths before A-levels start, instead after one month of learning you will do a test and you have to get an A or A*, how hard should that be? I want to possibly do a computer science degree but I might just go to uni, will not doing a computer science degree ruin my chances of doing a computer science degree apprenticeship?

Did you mean to say a computer science a-level?

https://www.ucas.com/ucas/subject-guide-list/computer-science

Scroll down to the entry requirements on this.

I think it's best to take computer science if you want to get ahead of the game and start learning it as soon as possible.

You could take further maths, but since it can be a hard subject you have to think about whether you can get a good enough grade in that subject to meet the entry requirements. They usually don't ask for specific qualifications, but it can help to have things like computer science.