Season's greetings, Thomas!
I'm thrilled to welcome you to the MERRIEST panel on Earth, planDisney! I can feel your excitement for the most wonderful time of the year, and at Disney World, it truly shines even brighter. The 
holiday season is absolutely one of my favorite times to visit. It's just pure pixie-dusted magic from start to finish!
You're in for the ultimate dose of holiday cheer when you attend 
Mickey's Very Merry Christmas Party! Where else can you sip hot cocoa as "snow" falls on Main Street, U.S.A., and wave to your favorite Disney pals as they parade by in 
Mickey's Once Upon a Christmastime Parade?! It's everything you love about Christmas wrapped up with a big Disney bow!
Speaking of characters, one of the best parts of Mickey's Very Merry Christmas Party is the exclusive meet-and-greets! While the full lineup hasn't been announced just yet, there are a few favorites you can look forward to. Over at Princess Fairytale Hall, you'll find Anna and Elsa greeting Guests in their holiday attire. Meanwhile, at Town Square Theater, Sally and Santa Jack are known to make appearances, as well as Mickey and Minnie in their merry holiday outfits!
Be sure to keep an eye on the 
Disney Parks Blog for updates, as more character appearances are often announced closer to the event. I'd also suggest downloading the 
My Disney Experience app on your mobile device. As the party approaches, you'll usually find a special event guide within the app that lists everything from entertainment schedules to character meet-and-greet locations, making it the perfect tool to plan your holly jolly evening! 
As far as 
Lightning Lane access goes, those are only available to Guests with a regular daytime admission to Magic Kingdom. They're valid until 6:00 PM, when the park officially closes to daytime Guests, and can't be used during the party itself.
I know that might sound a little disappointing, but here's the good news...because you have a party ticket, you can actually enter Magic Kingdom at 4:00 PM! That gives you a few extra hours to experience some of your favorite attractions before the party begins at 7:00 PM. Then, once the event officially kicks off, you can focus on all the exclusive holiday fun that makes this event so special! 
Thomas, I hope this information helps make your holiday visit as magical as can be! May your days be merry, your nights be bright, and your trip to Walt Disney World be truly unforgettable. And of course, we'll be here at planDisney whenever you're ready for more tips and holiday cheer!
Merry Wishes,
Kami