Your recommended area is the beautiful Leeds Castle in the county of Kent.
Here's an extract on Leeds Castle in our recent post on the castles of England >>>
Just 30 miles from London, sits the 900-year-old iconic Leeds Castle. Once the home of Henry the VIII, the castle today is considered one of the most beautiful in England. With more than 500 acres of beautiful park landscape and formal gardens, the stunning site features breathtaking vistas that will entice you to return time and gain.
There are more English castles to explore here.