Mature Student applying for Law - HELP!?

I'm 20 looking to apply for Law however I have had over 20 operations from Spring of Year 9 all throughout my GCSEs and A-Levels. I am currently sat resting one week post operation however it is FINALLY my last operation so looking to get my life back on track!

I only have 10 GCSE's (4 B's and 6 C's with a B in Maths and English Lit and a C in Lang) and A-Levels in Geography - B, Religious Studies - C and Media Studies - D. The head of Media Studies believed myself and a few others on the course were unfairly marked and I was "marked" as a B grade (what I was expecting and predicted) and they are also willing to do a reference. They were unable to re-mark as everyone in the year group had to agree to be re-marked and a few people didn't want to.

I was at University studying Fashion Merchandising Management however I had to drop out at the end of Semester 1 due to ill health & also being unhappy with the course/uni. I did however realise whilst doing my law module how much I enjoyed it and excelled (getting a 1st) etc and it all just made sense.
I'm now working full-time in the banking sector in a highly regarded position (for my age!) and looking to start doing A-Levels as a private candidate doing the fast track course alongside working full time.
I'll be classed as a mature student as I'll be 21 from the start of course also.
I am thinking about doing Government & Politics A-Level and Pyschology. However, I am slightly concerned that these aren't "strong" enough choices. I'm hoping to mix it in with my Geography B grade and RS (C). I know I'll be able to get A's in both Gov&Pol and Pyschology but I always see people stating to do History/English Lang/Lit/sciences/maths but I am concerned I wouldn't be able to gain A's in this whilst working full time and doing an open course style learning.
Has anyone got any advice regarding A-Levels and also universities outlook on mature students qualifications wise?

Any help/advice would be much appreciated