Insurance for holiday travel
The Isle of Man is not in the UK or EU.
Take out international travel insurance.
Equally UK residents need to do the same because IOM is not part of the UK National Health Service.
Yes, they will attend to you in the Accident and Emergency department of a hospital.
No, they will not cover £20,000 for an air ambulance to get you home in injured fragile condition.
Check Health insurance when travelling
So for anyone from UK and EU download this information leaflet (PDF).