There are some mock interviews and videos of current students talking about why they chose Cambridge which are all made by Emmanuel students on this youtube channel.
The interview is often portrayed as the most important and nerve-wracking part of the admissions process, but honestly, it isn’t that bad! The interviews are only a part of the information that admissions tutors receive about applicants, and they’re looked at alongside your predicted grades, teacher’s reports, and your personal statement to assess whether you’re right for Cambridge, and whether you could cope with the course.
Secondly, forget all those myths you’ve heard about interviews, because they’re not true. Interviewers simply want to see that you’re enthusiastic about your subject; they want to see that you can think about issues analytically and form your own opinions. They can’t achieve that by behaving in a crazy manner or trying to freak you out - they understand that most applicants are nervous and they take that into account. So don’t stress too much about the interviews.
A little preparation can help you feel more confident and may come in useful For example, read the newspapers because interviewers may often use current affairs as a starting point in discussion. The interviews aren’t there to test your knowledge, they’re there to test your academic potential and commitment to the subject, so it’s also useful to know a little about developments in your subject area.