There's quite a bit to do and see. My mother was born and bred in Folkestone (just down the road). My father was billeted in the Gun Battery on top of the cliffs for a short while (AA guns) during WW2 before being shipped off to India. I'd seen most of it before it became National Trust, it's much safer now.
Slack, thanks so much for telling me about your dad, I found it really interesting. Love that link to Dover castle, looks really very interesting, somewhere I'd like to see.