[Marc]

Ermmm... You should let people in still and stop at 00:00 exactly. Have somebody at the door so when it gets to 00:00 he/she can just say "I'm sorry we're closed now, these guys in here are our last customers". And just ask the people who are being served to leave as soon as they can, or when you're serving them let them know they can't sit in and they must take the food away.