[calibrax]

Perhaps somewhere near Maidstone or Sittingbourne would be most central for people in North Kent? For example, Ashford is a bit too far east for someone coming from Dartford, and Cudham a bit too far west for someone coming from Ashford.

I'll be happy wherever it is, as long as it's within 40 miles or so of Rochester.

Can't really suggest anywhere, as usually when I go out to places they tend to be near my work in West Sussex...!