What can a school do about a dangerous driver?

It is a police matter. Do you have a Safer Neighbourhood Team or equivalent?

Police with details. If you fancy a bit of vigilanty stuff use a fake facebook ID and pitch in on the (bound to be) school page or maybe the friends/PTA group. You may have an interactive link with school such as Seesaw as well.
It's really name and shame but maybe it might get through or at least to his kids/other half.
Send him to Coventry in all respects and make sure he knows why.
Good chance it doesn't work but worth a try?
If you have support maybe some confrontation or picketing of the pick up area.