Open seating from 7.00 or 7.30 until the time they close for new people (not sure about 9.30 I think). You can come to eat at anytime during those opening hours of the restaurant.
Evenings are still casual on the PG. A nice dress or pants outfit is fine. Nothing very fancy. Personally I dont think there will be many times you need inbetween clothes from the daytime until you change for dinner. Pack light seldom do people use all they take.
