I need to build for my site an appointment system.

Hi,
I need to build for my site an appointment system. The logic is that the appointment system is for an virtual medical clinic, where the pacients must fill a standard form and choose what doctor they want to make the diagnostic. After that, the pacient will be redirected to a paypal gateway. On the other side, the doctor will receive a notification in his account and email.
I need that the appointment table to display only if the doctor is available (daily availability) to take the appointment. In this case I don't need the table with days and hours and I wonder how I could make the doctor available/unavailable to take the appointments.

Thanks,
Catalin