Oh, South African or Australian…whatever. Just saying, I can tell. 🙂
I went to Machon Raaya, and the pleated skirt rule was only for class. On Shabbos or during free time, you could wear whatever you like. Not entirely sure about BS or BYA, but I’d say they don’t have the pleated skirt thing on Shabbos either.
Just a note – most Shabbosim aren’t hosted in sem (across the board), so you don’t have to worry much about fashion shows.