I assume you are ok to do normal non-christmassy things? If so, here is what I would do, it might give you some ideas?
Clean behind the cooker
Learn to knit (but I already have needles and yarn)
Declutter the marie kondo way, you can get the basic instructions online
Bake (if you have ingredients)
Sort out paper photos
And digital ones, label, put in albums etc
Do yoga with Adrienne on YouTube
Sort out Christmas telly, watch interesting stuff e.g. literally anything on BBC4.
Join in with Sarah Milligan on Twitter. I don't have a Twitter account so would have to join, learn how it works etc between now and then
Go out every day. Doesn't matter where or when, just walk for a set time then come home.
Have a really good look through the Martin Lewis website and get a really good understanding of my finances.
Join Facebook groups e.g. decluttering group, Hygge group, funny cat video group. You don't need to add any friends if you don't like fb, I had an account a few years ago like this.
I hope you can get some ideas from this?