I don't know what you consider long drives, but Scotland isn't actually that big. You can easily fly into GLA or EDI and reach the Highlands (e g Fort William or Inverness) in a few hours by car. Since you're planning to spend a week, you can see a lot of it.
The sort of barren landscape you describe is all around once you get north of Fort William-Inverness. It is indeed amazingly beautiful. Don't forget the islands - Skye has a bridge to the mainland, and the Hebrides is easily reached by ferries.
July is prime tourist season though, don't expect to be alone even in the most remote areas.