Myself and my better half did something similar last summer, struck out from the glorious Kyles of Bute (well worth a look) to John O'Groats (not really worth it) and spent the next three weeks working west and then south down the west coast.
Places of note, Dunnet Bay (CC Campsite, very good, nice beach), Durness: Smoo Cave, Sango Sands, Scourie: cracking fishing, Handa Island for puffins and amazing sea stacks, not much in Kinlochbervie, but if you continue out the road to the north west there' an amazing beach at Sheigra.
Sheigra was the highlight of our holiday, a lovely wild camping spot with an honesty box at the end of the road. Lucky we had the land rover and we got the best spot on the beach, there was about 4 other cars there. Got over the week brook and into a nice dip sheltered from almost all sides. We caught our own dinner of sea trout (this was early june) and sat up drinking wine beside our Braii and watched the sun dip for just a few moments. Dont tell everyone about it though!!!
Lochinver has the best pie shop in the world (even Micheal Winner says so, ahem), Clachtoll: right on the beach run by a lovely couple, the site it currently being developed but still open, Achiltibuie: cracking resteraunt and friendly locals (go to the Ceildh there's one on!). Ullapool is a nice stop, feels like the big smoke after all the wee places! Campsite in town needing some tlc and 20p for a 2 min shower is having a laugh, especially at the price of a pitch.
Gairloch, Poolewe, Isle of Ewe, Applecross, Plockton (Hamish Macbeth village) and then Skye all definately worth a look, especially for the Bealach-na-Ba near Applecross. Not much in the way of off roading though, but stunning scenery.
We're doing the Hebrides this year, but we were so taken with Sheigra we're trying to factor that in again too!
Have a great time and dont forget the Avon skin so soft!!!!