Hever is one of my favorite historic stately homes to visit in England. Unfortunately a few decades back a prior owner built a convention center/hotel on the property, which I consider to be a complete barbarism.
I was just there in August 2019 and there was no convention center/hotel on the property. The cottages behind the castle itself are available to rent for overnight stays, but other than that there is only the castle and the beautiful gardens, which have a quaint little shop where you can purchase gardening utensils, flowers, and seeds, and then a little cafe with just a couple of tables where you can purchase ice cream and drinks. The cafe sits right near the lake on the property; it's all very tranquil and very queen, and you feel quite removed from the world when there. There is also a delightful church, dating to Tudor times (and perhaps even earlier, if memory serves) right next door to the castle, that adds to the feeling of having stepped back in time. It's a beautiful place to visit.