Hiya! :-)
It seems that Virgin don't have a set pattern of letting people know whether or not they have been successful. I attended an interview a couple of months ago and I got the bad news that I wasn't successful 2 weeks after my interview by letter. However 2 of the people I met at the interview had to call Virgin themselves 3 weeks after thye interview to see what was happening. They were both successful. I've also known of people who got phonecalls the same day or next day. It is so hard to know!
I know how horrible the wait is though! If you don't hear within 2 weeks I would advise you to give them a call. In the meantime keep yourself as busy as possible and it would do no harm to keep looking for alternatives.....just ncase. ;-)
Good Luck!
:-)