Hi Mate,
I took my passport, NI proof and drivers license with me but it was not checked. I was surprised that I was not asked any questions about the company, however I was prepared. The guy who took my interview was "old school" if you get my meaning and I felt that he wanted to get to know me and make a judgment. However he did say that it was a formal structured interview and that he had to ask the same questions to all candidates.
The medical was nerve wracking for some reason, having worked as a conductor before I am used to medicals, but when I got there although i was relaxed when she took my blood pressure it was 167/110. The night before it was 124/80 which is normal. She took my pressure several times and it was coming down and she took the lowest reading which was high for me, but hey I passed.
Good luck with your interview, if you have anymore questions let me know