Chem and bio is fine. Maths may help slightly with the BMAT. Physics doesn't.
Further maths is not recognised by a fair few med schools. The main reason for doing it would be if you are not certain on your degree choice and might need it for something else, or if you are doing it purely for interest/enjoyment. It might also help with the BMAT, but given the above i would not take it if you are 100% doing medicine.
There is no need to do 4.