Cheers for the info Aleem.
Sorry if I made it sound as if earning a living as an instructor was imposssible. It isn't impossible, just very tough. If you love it enough I am sure you will make it work for you one way or another.
If you are at the Uni you are spoiled for choice with MA (they even have a kendo club, which is almost impossible to do cheaply as a non-student in the UK). If I were in your shoes I reckon I'd pick one art that I really enjoyed training in and use it as a foundation art; friendly people and instructors, and clubs elsewhere in the UK to continue in after graduation would be a key factor if I were choosing. Wing Chun might be a pretty good choice where you are.
Normally people advise against cross training early on, but Uni is a special case. I'd dabble in as many other arts as I possibly could whilst at Uni, even if only for a one off intro lesson. You probably won't learn much in that time period, but it is good general knowledge. The clubs are cheap for students and it is a great and really convenient opportunity to get a glimpse of different arts. Even if it is confusing and slows down early progress in your main art, Uni is an awesome place to get a feel for the different arts that are out there. (Definitely try out the kendo! Is a lot of fun)
I like the fact that you are looking at the town clubs too. A lot of students are reluctant to do that, and it can lead to missed opportunities.
If you are training in a town club you may be able to set up a Uni club off-shoot and get the instructor in - endless possibilities!
Perhaps also have a look at Systema, there is an instructor called Rob Poyton in the area. I've only done a class or two in Systema, but it is an art with depth and subtlety to it, and seems pretty effective; I hear good things about the instructor.
http://www.systemauk.com/index.html
Anyway, it is all personal opinion, so look around and see what grabs you.
Feel free to PM me if you have any questions - haven't lived much in Cambridge for the past 15 years, but I grew up there and know it pretty well still.
Good luck with the training and have an awesome time! Had a quick look at the Uni club sites and there is a good range of stuff there - would love to be doing the Uni martial arts thing again!
Cheers
Dan