1x interview and 1x test
Went over questions in the test.
Read around your subject.
Don't be scared.
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 an interview in December. I stayed overnight the night before and went to have a look at the Computer Lab in the morning. There were various students around to chat to us, and I socialised with other candidates. I had a
Discussed the contents of the
Read "The New Turing Omnibus". It contains am introduction on lots of subjects so is useful as you have a broad basic knowledge.
Don't be scared - just relax and be yourself, and try to forget that it's an interview. Mine was more like a conversation.