I was in the exact same position with a PE visa that expired and had many more Covid extensions than yourself. I flew back to the UK to get the Non O and got back three days ago no problem. The route you are doing coming in on a 30 day will mean you have to apply for a Non O inside the country. You will have to extend the exempt by another 30 days to get enough time to apply. Also when you do you have to show 800 thousand in a Thai bank in your name only and it has to have come from overseas. Applying for the Non O outside the country means you don't have to show the funds came from overseas when applying for your extension. Whether they let you back in on a 30 day is a risk. You may or may not be accepted but be prepared to have at 20 thousand baht in cash on you and a ticket out within the 30 days and accomodation.
You need to print it off for immigration. Also your boarding card of the flight you arrived on, visa printed if applicable and TM6 landing card filled in to present to them.