Here are some practical steps to have a good time and keep the focus on your goals.
1. If you are going to have a "cheat moment" try sampling. Get one or two of each item.
2. Having a beer or 2? have water with it. This will help you from over indulging and keep you hydrated so you won't get hungover.
3. Bring a dish you know is on your plan and that most people will also enjoy.
4. Just want to snack? Eat the nuts and veggies. Plenty of protein and fiber.
5. Be guilt free, if you mess up tomorrow is a different day. Get back up and try again.