Need help choosing a-levelsWatch
what do you want to do at uni / after A-Levels?
For chemistry you can pair it up with physics. Particle physics and chemistry works well together.
Maths A level does help with the maths content in chemistry but is hardly necessary, you can still learn it, it'll just take you a bit longer (e.g logs).
If you want a job that pays over 40k (I'm assuming you mean straight out of uni), you want to go for things such as banking and city law firms etc. For a lot of these, specific degrees are not necessary (for law you can just do the one year law course after you complete your degree).
It's hard to help you as you haven't given us much info, if you can be slightly more specific I'd be able to give you better advice
Also, on the side, don't just chase the jobs for money, if you do A levels and a degree to get a specific job for a specific pay (especially if you don't like them), you're making your life more miserable than necessary. I know someone who got into investment banking with a history of art degree, so anything is possible