"Why do you want to be a nurse?" was the first thing they asked us in the group interview and we went round in a circle and all had to answer. You should have stuff to say ready before the interview to be honest, but it's all common sense, it's really up to you to have stuff to say. And everyone gets a chance to talk, some contributed more than other people, just have your own opinions sorted in your head before walking in.
They gave people individual interviews if they feel they could have done better than in the group ones, but nobody I heard of got an individual interview, cos it's really hard to mess up a chat, really. Just relax, and since you're applying to nursing, you must already have an idea about why you are and what you hope to do with it. Absolutely nothing will come up that you don't already know.