A calendar tells you a client picked a time slot. It doesn't tell you whether that client has completed a suitability screening, given informed consent, or whether their intake data is stored in a way that meets UK GDPR requirements for health-adjacent information.
Trance OS's booking flow includes a GDPR-compliant intake and suitability-screening step (Suitability Pathways) as part of the booking itself. Reminders go out by email, and by SMS via Twilio on paid plans.