I tend to think of Christmas as a month in December/ Winter. It's getting colder, wetter and darker, icier and there could be snow. We need warmer clothes, solid shoes, heating in our homes. Entertainment so we don't go stir crazy. General health tends to suffer, and mental health can be affected for all sorts of reasons, unreasonable expectations, money woes, anxiety, loneliness, lack of support etc.
It's the hardest time of the year for many people already, and I think another full lockdown, would cause a lot of misery in itself (the forced isolation, loss of earnings, and potentially financial security, for a start).
We have about 12 days, and then Christmas technically starts. Advent calendars will start counting down until the big day, people will want to meet to exchange gifts and catch up, start stocking up for time off/ in general, (but still have to go out last minute shopping for that thing they need but inevitably forgot).
People on reduced earnings, will struggle more, particularly those on minimum wage, where 20+% of not much, can suddenly be the difference between being able to afford internet, to run a car, rent or mortgage payments.
36 days is not a lot of time to make changes. Symptoms can take two weeks to spread. We won't have a full idea of transmissions this week, until about the 3rd Dec, and then after that, the 17th, 8 days before Christmas, and not long before bleak, cold, skint (but coming down with bath sets) January, which already seems to last about 100 days, at the best of times (iykwim).
I don't know what the solution is, but I don't think another full lockdown is it. I think there should be more practical support for people choosing to self isolate (for themselves or loved ones). Help with shopping or ordering shopping, prescriptions, easy access to furlough schemes to allow them to stay off work, if it can't be done from home. Mental healh support. Allow the the most vulnerable to protect themselves with voluntary shielding, and let any of us who would probably get mild symptoms, try to keep the economy going, businesses from totally floundering, and a certain amount of normality, for vulnerable people to return to.