As soon as you buy your tickets, talk to your parents about your intended plans for the evening and make sure you're on the same wavelength. Respect their response and realize it's because they value you above all else. Be fair to them and make some compromises. You may not need a limo and a hotel room with your sweetie to have fun.
If you handle this situation with maturity and respect, your parents will probably reward you with more privileges later on. One really obvious, oh so simple, but important thing? Being honest with them. It's amazing what you'll accomplish if you give it to 'em straight.