I do bio chem and latin (yr 13 now) and I could apply to every uni except cambridge for med (they basically want bio chem +science/maths). You really don't need maths for bio and chem- there's one or two topics where logs come up but you can definitely still understand them without maths a-level. Most of the maths is GCSE standard but the wording/theory just gets a bit tricker.
Chem is the worst of my 3 subjects but the maths isn't really the hard bit. If you find GCSE fine and do higher maths, your maths is absolutely good enough to do chem!
I chose not to do maths bc I think I would have really struggled and not enjoyed it at all, but I loved latin and knew I could get the grades I needed (plus having a non-stem subject makes your timetable a bit more interesting!) and I knew that I was going to have to focus more on chem. Do maths if you want to, but uni's really don't care what you do as your third subject. Med applications are hard and it's in your best interest to make A levels easier for yourself so u can focus on the rest of your application.
oh also someone else in my year is applying for med and does bio chem art so you can definitely do it! just double check course requirements before you apply to unis in case it's changed.