Can you do medical physics with a natural sciences degree?

I'm really interested in doing natural sciences at uni but I don't know what job I would want when I'm done. Atm I do physics, chemistry and maths a level. I was interested in medicine but I don't take biology, which is slightly problematic... I started looking at medical physics and I think that would be better for me than medicine and something that would interest me more. I can see myself getting a job in this field when I'm finished with uni. However, studying natural sciences at uni and choosing both the physics and chemistry topics appeals to me much more than studying medical physics. I'm just not sure what I would do with a natural sciences degree... Is it possible after doing a bachelors in natural sciences to do a masters in medical physics? Or something like that? Or should I just look for a medical physics bachelors course and forget natural sciences?