Why are you afraid of taking her Jon? Just wondering like! There's no problem no matter who your with, what you look like or how old you are.
As for the club pass I would definatly wait till you get out there, you might get a 5 day club pass which allows you into 5 clubs on one day each, then find out all your favourate nights are at Pacha. Or I've heard of passes that restrict you to certain nights so you've paid for nights you don't fancy, then have to pay again for the ones you want.
Just buy tickets on the day, you can get them anywhere and everywhere. Passes are a no no IMHO.