There are universities that do not require biology. It is likely to limit the universities you can apply to if you don't have biology though. As long as you're happy with that, then fine.
Realistically, biology A-level is going to stand you in good stead for medicine, as lots of the preclinical bioscience modules will use that knowledge. I know plenty of people who have done it without A-level biology, and they have managed, and it's perfectly possible, but if you still have the choice, it's worth seriously considering doing biology.