There is a similar thread to this a few days back, and someone else mentioned and M and S indivisible beef Wellington, which would absolutely get my vote, along with pre-prepped veg. Maybe Christmas pudding ice cream for pudding (Sainsburys).
Naice ham, bread, cheese, crackers, olives maybe salami for your snack meals
Smoked salmon and scrambled egg somewhere
Croissants
A posh box of chocs
Posh crisps
Depending how into booze you are - some fancy half bottles. Or if you are more the low rent drinker, some fun minis. But either way, good red and fizz. Sparkling water so you don’t drink too much. Posh orange juice for your posh breakfast. Gin or Sherry etc
Also plan what you will wear - whatever mood you want to create you want to feel good
Similarly decorate a bit - a table top Christmas tree, Holly, fairy lights around the fire place
Plan your menu everyday, your entertainment and a trip out.
I would plan
- 3 great films. Varied moods
- order 3 great books (proper books) ditto
- 3 good bits of telly
- a fun streamer binge watch (you could just start it, although I could well imagine spending a day at Christmas under the duvet watching the crown / Bridgerton / outlander
- a podcast or two you would like to try (having the radio or podcasts on us good for background hum)
Go to church! I would! I’m not religious but midnight mass and/or a carol service
A couple of good walks - one to get holly, one to a fun local place (maybe somewhere with Christmas decs)
A play or the theatre if you have that around
Go admire/lust after/point and laugh at the hunt on Boxing Day (if you rural)
Christmas dip with wild swimmers! (they are frogging everywhere!)
Check your local paper, there will be all sorts going on - get out to some things
Bliss mass is a great way of putting it