thehouseofmirth you want south hams area then imo. Near a few different beaches and near plymouth, plymstock, dartmouth, totnes, Modbury if (MIL likes quaint) for shops and other things to do. They are beaches with a beach hut and a coffee place type beaches, not funfair beaches. And some, have nothing at all, not even a loo
Are you camping, holiday rental, hotel? You want to look at Brixton, Yeampton, flete estate, Bovisand, wembury, bigbury, and all around that kind of area.
North Devon is also fab, fab fab for beaches, but perhaps not so great on towns. Although perhaps there are some at Barnstaple, and it is closer to cornwall, not not that much in it.