Oxford Maths Interview

Hi, I'm a recent Oxford Maths grad- congrats on getting an interview and good luck! I can only speak for the interview process when I applied but to my knowledge it hasn't changed significantly. You should definitely know all the MAT content really well as they will expect everyone applying for Oxford to be familiar with it. With my three interviews, all the topics could've come up in the MAT. One was based around series, one around functions and one was a logic-based question similar to Q5 in the MAT. If they ask you about an area of maths that you haven't covered yet in school then speak up and ask about it. Being quick to learn a new concept in the interview would reflect very well on you and the tutors want to help you suceed. They have a genuine enjoyment and interest in teaching you maths. It is worth practising any and all questions that you can find. You should also practise talking through your answer out loud with every question you do. If you haven't already covered all the MAT papers then definitely complete those. Then look up past interview questions online - plenty of Oxford and Cambridge colleges release sample interview material. You should practise plenty of graph drawing and there are also good websites out there with "brain teaser' style maths questions (eg: Nrich, Brilliant). I would then look at doing some STEP I questions and if you run out of those then do Olympiads (probably start with Intermediate - Hamilton or Maclaurin papers).
Don't let the volume of materials here stress you out . It is absolutely not necessary to complete any or all of these suggestions before your interview! The tutors are looking for potential rather than knowledge and probably the most important part of preparation would be a week of lots of sleep. Best of luck for your interview.