from all accounts the palladium is full of little girls in Dorothy dresses at the moment. I much prefer green myself!!
Seriously there is no dress code. Whatever you feel comfortable in. I like to dress nicely to go to the theatre but occasionally I have turned up on spec in whatever I happen to be wearing at the time.
Just in case you thought I'd gone a bit crackers Elphaba is the name of a character from Wicked which is the story behind the witches from the Wizard of Oz - and she is green as opposed to Galinda's blondeness