Yes, And unless you go to a private school, you should have no problem wearing it. As far as I know, kilts are not banned from schools, as long as they are worn properly.

You proabally should notify the principle, but it is formal dress and I doubt your dress code exclude kilts. If you ask permission, they may say no (in which you can fight it unless the dress code for boys state no kilts, and I am not talking one that says no guys wearing dresses or skirts.) where as when you say politely that you are just notifying them that you are wearing it, and that it does comply with the dress code (you might want to give some history of the kilt) .

Hmmm, that is all I have. If you are taking a girl, you definantly need to get her on board. A tartan sash in black watch is a good idea.