Hello Mel
Well done for getting to the interview stage to be a crewing officer. My advice to you is just to be yourself and treat the interview as a 2 sided information exchange.
As far as i am aware there is very little reading material out there on the highstreet relating to the job i do and you are trying to get into. You could try dropping in such terms as FTL (Flight Time Limitations) & FDP (Flight Duty Period).
One thing i would do though is to research the company rather than the job but if you're really keen go find yourself a pilot to talk to and ask him/her about the subject.
Good luck!!!