If you are due to have surgery you should continue to prepare for it unless told otherwise by your clinician.
If your surgery is rescheduled for a later date you should monitor your symptoms closely. If your symptoms get worse and you begin to feel unwell you should report to your GP, call your valve clinic or in severe cases go to A&E.
You should also physically distance yourself and avoid social activities as per government guidelines.
If you have had a cardiac transplantation or are a pregnant woman, with serious cardiac problems, you should quarantine within your home.