Cases are currently falling, the government has the opportunity to prepare the groundwork for the run up and the christmas week to allow for christmas to be held relatively normally.
If they don't do this then many people will lose their jobs, billions will be lost from the economy however the end result will be that people will ignore the rules anyway and cases will still rise.
They need to facilitate through guidelines and rules how people can mitigate their risk to others. They should stipulate how to mitigate risk through prior self-isolation, place limits on how many households can gather and set the time period to a few days maximum (24th, 25th, 26th).
If cases are low enough then the effect this will have on new cases is irrelevant compared to the risk you currently face by going to work or your kids going to school from now until mid-December.