If you've not gone yet... try the Isle of Purbeck. If you've got the legs and the patience (and the good weather) go to Flower's Barrow Hillfort above Worbarrow Bay, but not from Lulworth Cove direction. There are many barrows, the occasional stone and some of the most scenic coastline in the south. Might be a bit far from Lyme Regis though.

Perhaps go north to Ham Hill near Yeovil? Its big, hillforty, its bumpy and got spectacular views over South Somerset (as well as a fake stone circle). Pop into nearby Montacute and go up the pointy hill (predictably called St Michael's Hill) - climb the folly at the top.