Hi Joe1234
The employer is certainly entitled to enquire of the employee where they were, and the employee may then give permission for the practice to confirm they attended. However, an employer does not have any right to get information from a doctor, even confirming attendance at an appointment, without express consent from the employee(who isn't an 'employee' when attending a GP, but is a 'patient' and the doctor has a duty to protect the patient's confidentiality).
Nicola