You think its warm now Soaring Sprog, wait till summer and don't think about ditching the long johns coz dress to survive isn't just about the cold, your shiny nomex growbag is vastly more effective against fire if you have at least one layer underneath it.
Top tip for the summer is bring your instructor a choc ice/ice pop as you come out for a running change, you get so many more brownie points to cash in for seats on formations, SCT etc.