Hi KML, i often camp at Burnbake Campsite near Studland, Isle of Purbeck. It's not very close to Kimmeridge i'm affraid, but may be one for the future.
Glo-worms, Nightjars, Deer, Reptiles, Hobbies etc can all be seen from site & there are some excellent heath reserves just a stones throw too.
There are showers and a small shop + you can also hire a picnic bench(bonus).
Bare in mind it does get busy during Bank Holiday weekends, so booking would be advised.