I've not been to a holiday park in a long time. I have a memory of staying at Butlins in Skegness when I was a kid and I'm sure that had a proper theatre. I would think some of the older ones might have better stages. Smaller parks will get by with the minimum they can. We did go to a park in Walton on the Naze where some friends had a caravan and their hall looked a lot like this one you show. They had seen the show there many times, but it wasn't my thing.