I've just started A2 for Chemistry, Biology and History. I dropped Maths after AS because frankly I was terrible at it.
Don't think you need 3 sciences/maths - chemistry you DO need, biology or human biology you will need for almost all schools, but there are some - for example Leeds - where the only required Subject is Chemistry. So you could do Chemistry, Archeology and Hebrew and get in there as long as your grades were good!
However you don't need maths or physics - so take a subject you enjoy and are good at!