Hi Claire!
Welcome to planDisney.
It's always a pleasure to assist my fellow guests from the UK, and I'm excited to see that your trip is later this month!
I have some good news for you! There is no party (Mickey's Very Merry Christmas Party) planned for the evening of November 28th! This means you can visit Magic Kingdom for the entire day, and will not be required to leave at 6.00pm because of a party taking place!
The schedule shows that Happily Ever After fireworks will take place in the Magic Kingdom at 8.00pm on November 28th. In other theme parks you could see Wonderful World of Animation at 8.45pm at Disney's Hollywood Studios; and Luminous The Symphony of Us at 9.00pm at EPCOT.
This calendar shows everything happening in the parks on that day. Please note that events are subject to change, especially due to weather conditions.
Enjoy Mickey's Very Merry Christmas Party, and have a lovely celebratory last night of your holiday! I know exactly how you feel!
Please come back and visit us if you have any further questions, and you can
send me a direct question if you wish. We are always happy to help you plan your magical holiday to Walt Disney World Resort!
Sue