Biology and Psychology have some nice overlaps. I can't comment on business and ComSci, but Maths is okay if you can spare the time to continually practice. It's not like science where you learn the answers, you have to see as many variations of each technique as possible. A concern may be picking Biology as the 'easy' science. Lots of people fail biology because they have unreasonable expectations for the subject.Ultimately, you need to chose whichever you will be able to motivate yourself to study for two years, and what will facilitate whatever you want to do with your A-Levels.
However, as a Biologist, I would like to say that biology is the best subject, and everything else you could possibly study is physics or pointless :P