To become a doctor (probably a GP), is it essential to take biology, chemistry, physics and maths at A LEVEL because I'm happy to do chemistry, physics and maths which I'm A or A* at GCSE, but I'm not keen on taking biology at A LEVEL because it will be too much and it is my least favourite subject out of the 4.

Any advice please?

Basically, yes, although physics is not really needed.
You'll defiantly need Biology, after all a lot of medicine is about living organisms.
Also you will need mostly A grades as places for medical school are very hard to come by.