Pay little regard to student satisfaction rates. The method they use to calculate it is laughable - a tick box 1-5 criteria - and it is very vulnerable to a small number of final year students bothering to fill out the form and universities putting pressure on students to give positive feedback (because it is an easy way to pick up league table points: look through some of the tables, a university with better research, entry standards, employment rates, staff-student ratio can be ranked lower due to student satisfaction, which is frankly absurd.) Imperial is an outstanding institution, as are Oxbridge and UCL. 78% course satisfaction is not awful either.
If you are interested in biochem it is quite likely you will do postgraduate study and/or industry work. As regards research, it's that golden triangle of London and Oxbridge, you can't argue with the resources and expertise available. Clearly career wise London has an obvious edge. As far as multi-faculty institutions go (unlike Imperial or the LSE which are very specialist ), UCL is undoubtedly the best university outside Oxbridge - look at global rankings in particular.
The thing you must do is visit a few places and get a feel for them. It is all very well looking at London, for instance, but if you don't like cities 4 years in London won't be very enjoyable. There are plenty of good courses around, it depends where you will feel most comfortable. Certainly, academically speaking Oxbridge and London would be wise choices, but there are good departments all over the place. Try and get a sense of what you want to get out of the experience as a whole and take a view.