In reply to Will Cat:
Its about 10-15min drive from Weymouth but Osmington Mills has a great site (see views) and v old pub.
Also see the two sites down the coast west from Portland. 10min drive maybe. Sea Barn and West Fleet. There's a good pub (Turks Head Inn) but it's about 2miles from the camp site.
I think that's your two (three!) choices.