One thing is for sure - we haven't been in Korea for decades. By the sounds of it you could do with brushing up on your current affairs. I suggest www.bbc.co.uk/news and for background info www.wikipedia.org
So long as you have a sound knowledge of what the RAF operates, where we are in the world and what you chosen trade involves, you'll be fine. When I joined I didn't find the interview particullary challenging. It was more like a chat about yourself and what you know about the service you want to join.
I'd say know the following:
Yourself. What you did at school/family/hobbies/clubs/sport/motivation for joining.
Why you have chosen CIS Specialist.
What recruit training consists of/how long/where it is.
What your trade training consists of/how long/where it is.
What your role as a CIS Specialist will be.
Where you could be posted.
A/C we operate and their roles.
Where we (the RAF) are in the world, and why.
Thats plenty for you to learn! If I think of anything else I'll let you know.
Better still, if you are under-prepared, give them a call and say "Sorry, I've done some research and realised I'm under-prepared. Please can I delay by one month". Shows you have done some research, you are aware of your limitations, you are serious about the application and you have the moral courage to face up to a tricky situation and plan a mature way to deal with it. Better than going in and making a complete *rse of yourself - really bad interviews don't usually count as useful experience.