Individual schools are already closing if they have links with the outbreak- so bear in mind that schools are gearing up for that possibility too, as well widespread closures.
The school where I work is stepping up hygiene procedures e.g. providing more soap, asking us to encourage handwashing and teaching good handwashing, no handshakes in school, hand sanitizer and wipes for touchscreens.
We already have various online set ups to enable us to set homework, so we haven't been asked to set up anything new to enable us to teach remotely. We were asked to remind Y11 of exam contingency dates, and not to book any holidays before this date.
The big implication of secondary school closures is the affect on exam results, of course. If they are rolling closures, rather than all schools closing, they will affect some children more than others and there might need to be special consideration given if an individual school has to close for a long time.
For primary schools closing obviously the big impact is childcare. Nurses in South Korea have actually been leaving their jobs due to the combination of 12 hour shifts and schools being closed. School closures in South Korea don't seem to have had that much of an impact on the spread.