c_jephcott,
check your PMs.
Mark, check the forum! Stage 3 is about being yourself and showing how much you want to be on wings. The interview is fairly informal, however you need to have a bit of knowledge on the wings scheme - the main airlines involved etc - they won't ask rediculous questions like the wingspan of a 737
. Just have a general knowledge of the website.
Apart from that take JediDude's advice - relax and enjoy, and don't start shouting and ordering people about in the team exercise(nor the interview)!
best of luck