regretting a level choices?

Okay so I mainly chose - Maths, Physics, Philosophy and Politics.
I feel like I should've done further maths instead of politics, because I wasn't feeling confident in it first, but now I'd really rather do further maths. Freaking out cause unis like Oxbridge prefer it aswell. I want to do astrophysics or engineering btw... Wondering if i can still do the degrees I want? Or if I can change my alevel options?

Your subject choices are fine.
If you’re really worried, you can maybe self study parts of the further maths course at home and put that on your personal statement, universities might like that as it shows you have taken the effort to study more maths and shows your interest. It’s up to you.

You’re fine with those subjects. Further maths is not required for any physics degree in the country, yes it may be helpful but you can get into pretty much any university for physics and engineering without doing further maths a level. Further maths is a bit of a novelty, I know someone who got into Oxford to study maths a few years ago and they didn’t even have A level further maths, they got into a maths degree without further maths.

Your subject choices are fine.
If you’re really worried, you can maybe self study parts of the further maths course at home and put that on your personal statement, universities might like that as it shows you have taken the effort to study more maths and shows your interest. It’s up to you.