I think she should go to a big complex that has an ice skating rink, a bowling alley, swimming pool and a burger joint and have some fun, she could hang with the kids, and after her day of sports recreation she should go back to the palace and sit back and enjoy a few tokes on one of Harry's fatty bumbattis
It will obviously be something low key, whatever she decides to do. Can you imagine the kerfuffle if she does something newsworthy on such a "special" day?
I guess she would sit at home on the estate and possibly arrange a shoot with some friends and tally on home for a quick tot of something, watch the telly and snort and dribble at the boyfriend and off to the country club for a skinfull, then bedibise.