We will be in the area at the end of September. How easy is it to get to tickets the day of?
No problem for us getting tickets at the entry around the third week of October 2021. Physically, it’s a big space so I can’t imagine it would be difficult for you during your planned visit.
I wouldn’t worry.
EDIT: I should add that the biggest challenge might be finding parking. Give your self plenty of time for that. As we were prowling around looking for a spot, an attendant in one of the small parking lots off the roadway motioned to us to turn in. So, we did and scored a spot a short walking distance from the entry. Upon returning I flipped him €5 for helping us out.
Peter, thank you for your helpful response!