Google Calendar can be effective, you can allocate individuals their own calendars and show the combined result if you wish. It will also send automatic reminders for calendar events.
This seems to be a specifically targeted product, which is unlikely to match the OP's exact requirements.
But back to the point about its growing use in the NHS...
my GP are using a service (which is pretty micky mouse) that appears to have been mandated by the area authority.
all of the surgeries in the region are using it, so it looks from the outside to be well supported,
but it was probably just one or two people (who from the looks of things didn't have the appropriate experience to make the choice) was responsible for that popularity based on, well I don't know what really, perhaps just the quality of the biscuits on offer when the company presented their product.
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