In reply to daveyw:
Portland Museum (bottom of Wakeham, the wide road going south from Easton), down to the belvedere overlooking Church Ope Cove (signposted). As you face out to sea, turn left and go slightly upwards. Following the obvious path, and contouring northwards, roughly in line with the coast, you'll see a little crag to the left of the obvious path that you're on. Carry on past this (the New Cuttings). You'll come out at the intersection with another path coming down, diagonally from your left. Ahead of you is a large crag. This is The Cuttings. Carry along for about a mile (obvious path) (not sure how far kiddies can walk!) - or not. Maybe better to come back the way you've come.
Having a good day at the Cuttings requires care (many polished horrors lie in wait for the unwary). But at least access is readily possible for all the family.
Mick