Sounds like the format of the interview may have changed for this intake if they covered all of that? They like the scenario type questions too like "tell us an occasion where you have improved a process" or "when you have dealt with a difficult customer". Always handy to prepare a few of them, they dont need to be work related.
Also, keep talking if you know what you are talking about. You cant give them too much info, they'll stop you when they have heard enough but be careful not to dig yourself into a hole. It's doesn't feel good to say "sorry, I don't know" but it's better than waffling rubbish. If you show them you have done some research and know about Nats as a company you'll get on fine. If you were able to visit a centre, that helps too but not easy if you are in Ireland.
Best of luck