Prevent a specific appointment type from being bookable within a set period

Handy for when a practitioner is going away and doesn't want to see NPs on the run-up (because they wouldn't fit in enough appointments before having a break in care). So to disable NPs from booking online during a certain period (on a per-practitioner basis) would be helpful, so that regular visits can still book in right up until the holiday, and NPs can book in outside of those times