Personally I’d go for closing schools a week early, with online learning or paper packs. Maybe a skeleton staff in school for the most vulnerable and a small number of essential workers, or small socially distanced groups for exam tuition.
Certainly in primary schools there’s a reason why that week tends to be more relaxed; children are tired (and will be even more so this year with the relentless drive to catch up, not to mention the joys of sitting in a freezing classroom for weeks on end) so it’s not an ideal time for new learning.
Secondary children could have a revision week - my Y7 dd has missed nearly 4 weeks this year, so the chance to go back over the main learning in each subject would be useful.
From what is being reported today it does look as if shops, pubs and restaurants are going to be reopening to some extent. I get why this is needed to preserve jobs and the economy, but it does mean that when schools go back in January the bubble is only as safe as the family that’s done the most mixing. However careful individual families are, children will be exposed to new cases on their return.
Many of the people who can’t afford childcare if schools close in January are going to have to cover two weeks isolation regardless - and then quite likely further periods of two weeks as well.
It all comes down to a gamble - a planned closure as a firebreak, vs repeated groups off isolating. Many people who don’t believe their children will be affected will be quite happy to take that risk, while others who’ve already been through the stress and grind of repeated isolations are maybe not quite so keen.