I think I was more nervous for my leeds interview than any other, but that's because it was my first choice. They try their best to be friendly, and I can honestly say that it was a good experience you learnt a lot about the course. From what I can remember, it started with an introduction by the head of the program, followed by a group interview/ maths test (the group was split in half), lunch, then the group interview/maths test.
The head of the program is one of my tutors, and she was saying that the maths test is significantly harder this year. In other words, most people did it in 10 minutes last year and they need to be able to prove people can cope with division without a calculator ( for example 3/7, 455/900 ect), so while I haven't seen it, be prepared for it.
Also from experience, I can tell you that more emphasis is put on how you come across in your interview than what grades you get (in my sake anyway). Last year I did pretty well in my interview but got BBBD in my A levels (one of the B's was in general studies so disnt count) and I still got a place