And if you do want to fly fast jets, study up on their tasks, where they are based and deployed etc. However, they may then show you a photo of a B707, and ask you all about them. So make sure you have an all-round knowledge.
Current affairs is also a big issue, especially when related to current conflicts, defence spending and the defence minister.
Don't bag any type of aircraft, for your interviewer may have flown (and loved) them. Once again, know why you want to join, and have an answer ready for why you don't want to join the airlines. You want to join the airlines in eight years? Keep that one to yourself - I've heard kids announce that pearl.
Find out about MDR - Mental Dead Reckoning. A good pilot instructor should be able to help you on that one. You may be asked a few aviation related mathematics problems, to see how you work under pressure. Your F-111 is being towed down the Amberley runway at 10kts, and is passing the 2000ft to go marker. Will it reach the turnoff at the end of the runway before the Hawk trainer which is 12 miles away doing 360knots flies overhead?
It might not be that exact question
but you get the idea. (Don't take a calculator).