Rather early this one, but here's a festive adventure seed for a possible Christmas special for your group's campaign. A more lighthearted affair if you will to add some levity to a campaign. Whether it is canon or not is entirely up to you.
It is Christmas Eve and your PCs have decided after recent events that they will take a break and celebrate the festive season together. As well as, in the event any of the companions are aliens, give them a chance to further experience some of Earth's culture.
The console room is decorated with lights, a Christmas tree specially cut from the Forests of the Nine Winds sits in the corner. (Don't get too close though, they have a tendency to bite when angered.) and a Christmas turkey is quietly cooking in the oven. Rather unfortunate then, that they seem to have misplaced the room that the oven is in.
Yes, all is well and it will surely be an evening to remember as they all gather to celebrate not only the spirit of the season but also this new family that found themselves a part of.
That is until a walking, talking nutcracker knocks on the TARDIS door asking for the resident Time Lord and their companions help.
Here we go again.....
As always, I'd love to hear any thoughts or suggestions.
I admit my first thought on reading this idea of yours was the nutcracker is looking for his wife a tree from the forest of the nine winds as I missed the bit about it being cut and thought the tree was an ancestor of the ones from the end of time and was actually sitting in the corner. Could work well for a story dealing with dimensional travel or a trap in the land of fiction with the nutcracker there to lure them out of the TARDIS's protection.