2 x 30 mins, MLAT
Unseen text in target language, discussion of text, personal statement, 5 minutes at the end of general conversation in the target language.
Texts mentioned in personal statement, unseen analysis, speaking in target language
Practice papers and grammar revision
Let them see that you love what you're doing
Remember this advice isn't official. There is no guarantee it will reflect your experience because university applications can change between years. Check the official Cambridge and Oxford websites for more accurate information on this year's application format and the required tests.
Also, someone else's experience may not reflect your own. Most interviews are more like conversations than tests and like, any conversation, they are quite interactive.
Test taken: Modern Languages Admissions Test (MLAT)
Number of interviews: 2
Time between interviews: a day
Length of interviews: 30 minutes
Online interview: No
30 minutes before the interview we were given an unseen text in the target language with an English translation and were expected to analyse it before we went into the interview in a separate room. Then, the interviewer asked me for about 10-15 minutes to explain my initial impressions, followed by some more specific questions about the text (e.g. the interviewer trying to flag anything I'd missed, maybe asking what period I thought it was from, that kind of stuff). After that there were about 10 minutes of discussions about my personal statement, mainly focusing on two or three aspects of it. Finally, there were 5 minutes at the end of general conversation in the target language.
I made sure I knew all the texts I'd mentioned in my personal statement really well, so that I wouldn't be caught off guard when they came up. I also practiced unseen analysis by asking my teachers to give me a range of poems/extracts to get used to that kind of activity. There is a 5 minute section at the end of the interview that is in the target language (ie French if you're applying for French), so it would be really useful for applicants to try and get some speaking practice in. However, if they can't, the interviewers are really understanding. I'd say it's more important to focus on the literary analysis side of things.
I used practice papers from around 2008 onwards. Because the MLAT is, above all, a grammar test, other type of preparation was just all round grammar practice. I went though my whole A level book and basically learnt all of the grammar for the year.
If the interviewer is challenging a point you made, it's a general rule that you first re-explain why you said what you said, to make sure your thinking is clear and hasn't been misunderstood, and to show you have faith in your own points. However, if they continue to challenge it, you've probably but unwittingly made a mistake, so best to agree with the interviewer and let the interview continue. Other than that, have faith in yourself and, as cliché as it sounds, let them see that you love what you're doing. The interviewers were really nice and it'll probably go by faster than you think.