Must agree with Jon,
Gairloch, Poolewe, and especially Ullapool.
I go to Ullapool at least twice a year, my dear lady has family there and we take the tin tent up.
The camp site at Ullapool is Broomfield, if you google it you can get the details, and is very reasonable and situated on the banks of Loch Broom. You can get the ferry across to Stornaway in Ullapool.
The site is within walking distance of the village, its almost in the village and Ullapool is a great base for trips to loads of out of the way places and fantastic scenery.
Tommy