Good luck for your interview, try not to be too nervous, the recruitment team are a bunch of nice people and they try to make the day as relaxed and light hearted as is possible.
Some questions I was asked in the final stage (2 on 1 interview)...
* Tell us how you have reacted when someone in authority has done something you dont agree with?
* Tell us how you reacted when someone in authority did something that breaks the rules?
* Why do you want to work for Virgin?
* When did you show exceptional customer service?
* How do you have fun at work?
* What will you do if you are unsuccesful today?
There were several more, but its been some time now and thats all I can remember! Maybe someone else could chip in and help... But anyway, start working on those, I was asked all of them and more.
Good luck, its a great company and we're recruiting really hard at the moment. Let us know how you get on!