Maths and Physics would be a recommended and safer A-level as a 3rd option but it’s completely down to you.
As someone currently doing 4 A-levels and wanting to study medicine, it is a lot of workload and it gets really tough. Doing 4 A-levels is not for the weak minded 😅.
Psychology is a good 3rd option. My friend does the same A-levels and she finds that there is a lot of crossover between biology and psychology which makes it easier for her. I would suggest you stick with just those 3.
If you really want to do maths then you can always drop it at a later point but I don’t think it’s necessary.