You really do need to do this soon, most people applied a couple of weeks ago.
None of the colleges is "the most academic". They all have the same mix of students of all abilities, backgrounds and on all courses.
But people will tell you that the quietest college is Cartmel. Yes, it is quiet, especially in the daytime, because it is on South West and people go up onto campus for lectures, and stay there all day. So there are very few people around college from 9 til 5. Whereas the campus colleges, esp Bowland, have people passing through all day long.
Cartmel bar is also quiet and not much used. Again, those who like to go out a lot go off campus or to other bars for their socializing.
Cartmel is not as quiet and boring as people from other colleges say, but as a person who likes peace and quiet, and my sleep, I have been extremely happy there for two years.