Go and speak to your local RAF careers office. They should provide you will all the information you need including the role of the RAF, bases around the world and why they are there, types of aircraft and role, the structure of the RAF etc.
In relation to current affairs, make sure you read or start reading a good quality daily newspaper and watch current affairs on TV which often give you a bigger picture of topical news items.
PM me if you need any further help. I have some experience of the selection!