I've done research on some universities in the UK to study Veterinary Medicine but none of the ones that I've come across specify if I should take AI or AA, the only requirment being Maths SL and/or the grade (e.g 5 out of 7). Some don't focus on the overal points out of 45 but more on the individual grades of subjects.
I've spoken to a few teachers, they said AA would be a better option as it'll give me more opportunities for universities but after receiving my prior knowledge test we did during induction for DP, I did not get a high enough mark and so my maths teacher doesnt recommend A