Just an outsider's perspective-one thing that is a bit different from England, Scotland and Wales compared to many other countries worldwide, including the Republic of Ireland, is the fact that England, Scotland and Wales lack content-specific curricula supported by standardized textbooks-and workbooks/exercise books do not seem to go home daily.
In Japan, ROI and actually most other countries, textbooks, workbooks and exercise books go home daily. This means that it is much easier to "pick up and run" when this kind of thing happens. The curriculum is already set out, and if the worst comes to the worst (example: a teacher has to be in charge of a classroom comprising a bunch of random kids of different years/ages), a teacher can just make the kids plod, page by page, through the textbooks and workbook exercisesit is not always terribly exciting but it works, just about. It's also far easier for a parent or childcare worker to "get a child through the basics at home" if they have toagain, not ideal but at least they will not end up with massive holes in their knowledge. Parents are much more aware of what their children are studying at school, how their child is doing at school, and what will come up next in the school year, meaning they tend to freak out less if they have to homeschool for a while.
In England, Scotland and Wales, there seems to be an expectation that teachers must hand-craft individual, endlessly differentiated lessons to a curriculum that changes a lot year to year and from school to school, and parents seem to have a much weaker grasp of what is going on.
Perhaps this is nice for pupils in a way (and also nice for parents in some ways--they have little responsibility compared to many other countries), but it must create a terrifically demanding workload for teachers. And it means that when something like this happens, there is no easy way to transfer to a basic bare-bones low-workload system where considerable responsibility suddenly has to be outsourced to parents. Everyone panics.