yeah the course is more important than the university - make sure you check course content, teaching methods and have a look at past papers to decide on what exact varient of biochemistry, bio natsci or bio/ chem you want to do first.
In terms of picking a college (at cambridge cos that's where I know about), you should think about how many people are in a year, how many others will be doing your subject at that college (it can be nice to have some ppl to work with in college), how phycially large/ how many rescources like sports facilities/ music practice rooms it has, what the rooms are like, and if u like the architecture and stuff. Also LOCATION is actually VERY important. Girton is a 20 minute CYCLE from central cambridge (where most lectures and faculties are) and many say this is a real pain. Pick a central college
Also be a bit strategic and don't apply to somewhere rly oversubscribed like trinity unless ur very confident as you could be POOLED TO GIRTON
also remember colleges can be much BIGGER than they look from the front gate. Emmanuel and Peterhouse, for example, have large gardens which you wouldn't be able to guess by looking at them from the street. Scrutinise the website carefully, and also bear in mind you might live in college accommodation away from the main college in some years. Again u can check this on the websites