I love TidyCal!
I have one suggestion for improvement... add a quick toggle to activate / deactivate available time slots.
Why this will make a difference.
It is a fairly tedious process to setup time slots. The issue I am having is that I often have to go in and cancel, or overbook time slots on my calendar because some external event or factor, will change my availability. If I could go to my calendar or bookings page and simply click on / off toggles for availability it would be super helpful, rather than having to either overbook a session, or remove it from the backend, and then reinstate it later - both of which are very tedious.
Hope this helps.
Guy