Want to travel by road from Phuket to Cha Am returning about 8 days later, anyone know what is required in order to make this return trip.

I am fully Vaccinated with Pfizer.

the only checkpoint is at phuket bridge. 

Just in case take with you some atk tests and do them on the spot.

I would do one just before leaving, just to be sure you are clean and don't end up as asymptomatic in a private hospital.

Take the very same test with you, write date and time on it, make dated picture of it.

In theory there is an online application for inter provincial travel, to be filled on the day of travel. For the sake of it you can do it - just a minute of your time