We recently visited Arley Hall as a day trip.
Although we went as a group we were expected to pay individually the full price to enter the grounds. There were no concessions. We were told that we could use the restaurant and visit the gift shop without paying. Some of our party were willing to pay to visit the gardens and the house but about half were not. We learnt later that the driver had had to pay for everyone even those who only used the restaurant.
The service in the restaurant was appalling. The woman behind the counter overcharged several people, although she did correct herself when challanged. We waited 25 minutes for our egg sandwiches to be delivered. When I complained, I did get a fresh pot of tea which was appreciated. Another of our party waited ages for a baked potato which was not fully cooked through.
Whilst I don't blame the management for the heavy rain, I do blame the lack of places to shelter. There was no facility for the coach driver to drop off or pick up passengers by the entrance. We all had to walk in the pouring rain some 500 yards to the coach park.
The prices were expensive but on a par with what you might expect. I noticed though that they were charging a surcharge on credit-card purchases.