I didn't have great advice for selecting my A levels and chose Physics without also taking maths, which I realise was necessary for what was required.
Instead of suggesting or requiring that I took up another A level ( I dropped physics in the first term, as did the only other female on the course, after being patronised one time too many by the teacher) I ended up volunteering at the local special needs school.
I also took economics and geography.
I cocked up the geography exam. You were supposed to write each of the 2 main questions into separate answer booklets, as they were being marked by different people I assume, one being physical geog, one being human geog.
I answered both in one booklet. Panicked at the end of the time. The examiner let me have a small amount of extra time to transcribe one of the questions over to the other booklet, but I ran out of time - and did it all in tears so didn't do it very well.
So I finished with a B in economics and only an E in geog.
Luckily, the closest college (now a uni) offered a teaching degree which I was really interested in after my volunteering. And they only required 2 passed A levels, so were happy with my B and E, and my Bs in GCSE English and Maths.
I enjoyed my course, made great friends and I've been teaching for 20 years now and still love it.