I've heard that some unis (I think one of them was UCL...) prefer you to have an art subject as well as science a-levels when applying for medicine. Does either Oxford or Cambridge prefer prospective students to have an art subject as well as the sciences? I want to take Biology, Chemistry, Physics, Maths for sure, and was wondering if my chances of getting in would be increased if I took an Art A-Level (probably either french or Philosophy/Ethics) as well?
No not at all. In fact, a lot of Cambridge colleges officially or unofficially want you to offer 3/4 sciences anyway. Doing the Art a-level wouldn't help at all for Cambridge. I would say something equally definitive about Oxford, but I have a bad feeling i'll be quoted by Elles lol, so ill let her talk about that.
If you've already got 4, the nature of the 5th is really not going to matter tbh. Not having a non-science might be a disadvantage with other schools though.
If you think you can manage 4 science A-levels (I personally didn't find the work load from Maths or Biology that intense, though Chemistry at times got pretty challenging), and then an Arts A-level (without it hindering your other subjects), then I personally think its a good idea. Surely it indicates versitality, and having an essay-based subject might fit in well with Oxbridge's tutorial system.