Even if they can "travel" at Christmas it will just be another cottage/forest holidays place not far from where they live anyway. Where they will do nothing but go in a hot tub, shout omg, it's soooo preeeetty at every piece of tat they receive. It won't help their views.
I kind of hope they won't be allowed to go, but then I know there are lots of good people who also wouldn't be able to travel anywhere for Xmas or see family, especially if they do not live near them. It's also possible that even if allowed, granny Jane might not want to join them to cook their Xmas dinner.
We're just going to be at home all day, if allowed will have a quick meet up with family day before or after. It was easier to just make the decision so everyone knows what to plan/food to buy, and the kids know what's happening so won't get disappointed with changed plans.
They can come home if they choose to, and will have to isolate. I think they were going to go to Lapland but I think that's cancelled anyway, and then somewhere else for Xmas itself - probably near home just to be able to dump all the unwanted gifts back at the house.