Hi, how about Torquay/Torbay this place has 2 bedrooms and sleeps 4 for about £700 for 7 nights in July and August school holidays. BlueChip have lots of properties in the area you are looking for and 10% off until 31st Jan.
This might not help but we always go with helpful holidays when holidaying in the west country. They have a good range of self catering places and have never had any problems and lovely places. We went to Kingsbridge a couple of years ago and liked it there - lots to travel around and see and nice town with all amenities. The villae of Salcombe near Kingsbridge is lovely.
We have stayed several times at a place calledHigher Poulston Farm, about 5-6 milesout of Totnes. We booked it through one of those holiday cottage companies. its not too far from paignton ,Torquay etc.