I've come out of hiding briefly
I did hide this topic from active convo's but well, you know how it is.....
It's been years and years since I did my uni interview so not sure I'd be much help, I'm trying to think.
When I did it, we had an individual interview, I think they asked about current mental health issues, as they were at the time, my skills, weaknesses usual stuff. Nowadays with the NHS undergoing massive changes and a shift away from in patient care, they may ask your views on that. What you see the role of a mental health nurse as. They may ask what you would do in certain situations. If someone wallops you one, 'I would wallop them back' would not be the correct answer

We then had a group task which was about something and nothing really, but I think they were assessing our group communication skills etc.
Good luck with it. Not an easy time to be training or qualifying I think. When I qualified I walked straight into a job, now we have newly qualified nurses working bank as they can't get jobs.
Mostly it's a great job though, very challenging but I've mostly enjoyed it. You do need a thick skin on here sometimes though. Hence why I hid the topic......
I hope that helps. You may get more luck in Chat actually.