No.
It's specifically set up so that you cannot over compensate in one section. They do this by requiring a certain threshold score in each section (I think it's 55 in section 2 or 3 with at least 50 in the remaining sections - or something like that).
This means that you can't get a bad score on the science and make up for it on the others.
Or, at least that's the idea for nottingham and st. georges. Swansea work it a bit differently. I don't know about the others.
The physics is almost ignorable, but the chemistry you will need a solid grounding in. I suggest "Organic chem for dummies" and A level chemistry books. You need to take the organic chem a little further than A level (hence the dummies book) but for the rest you should be ok.
Remember, non science grads do better on the GAMSAT than science people.
Enjoy
