Good luck with your assessment. In your interview show total focus to customer service and safety. I am not sure where you are located by why not go to say Lewisham on a Fri/Sat evening and see how the staff there deal with very large crowds, cancelled trains and very often frustrated & intoxicated passengers. It would certainly impress me if I was interviewing you and you said you had done this. Also when it is quieter go and speak to platform staff at a busy station (ideally a supervisor)- tell them you have an interview and if they can offer any advice or tips. In my short time on the railway it has always impressed me how much people want to share knowledge & help. In my previous career I must have interviewed hundreds of candidates and it was always the one that had done that bit extra on the research side that got the role (all other skills being equal)