Two 30 minute interviews - a friendly experience
Your personal statement might be brought up.
Take advantage of resources on YouTube by Cambridge University
Wear what you feel comfortable in.
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.
I had 2 interviews: each 30 minutes with 2 interviewers. They were in the morning with about 2 hours between them. Before my first interview and between the interviews I waited in the JCR and there were lots of first year students helping who were really friendly. They took us to all our interviews and waited with us until the interviewers called us in. One of the first years even came up to me elsewhere in Cambridge that afternoon and asked me how my second interview went - it was such a welcoming environment, and there were biscuits.
The first interview was very chemistry based. It was very difficult and I didn’t understand some of the questions. The second interview was friendlier. I was asked to talk about something that was on my personal statement, followed by some (fairly easy) maths questions.
You really don’t need to wear a suit, even though your parents will probably tell you to. I went in jeans and my favourite jumper and things went quite well for me, so just wear what you feel comfortable in.