Im currently doing A2 Further Maths, Maths, chemistry and physics.. To be honest, I don't think biology is necessary for you ( i was going to take biology as well but i thought that there will be too much work to do and it will affect my grades on other subjects, the subjects i have now are sufficient for chemeng).. Just concentrate on your four A2 subjects and that's pretty enough.....
Cambridge is the best for sure^^ Although it is highly competitive, do aim high and apply if you get straight As in your AS.
I heard loughborough is a good one although I didnt apply...
other good ones are imperial college, leeds, bath, manchester, newcastle, ucl etc..