Here's what we did.
We figured we couldn't do both countries justice by car in the time we had, so we flew into London and just did the city for ten days without a car. (You don't want to have a car in London .
)
(We then visited friends in Switzerland for a week, but ignore that.
)
We then flew to Glasgow, spent two days, rented a car, and drove to Oban via Trossachs National Park. The next day we drove to Mallaig, took the ferry to Skye, and drove to Broadford where our B&B was. We spent a few days there, drove over the Skye bridge to Inverness along Loch Ness, visited the Glenlivet distillery and drove to Braemar (where my family is from); you might prefer to go to Aberdeen instead but Braemar is very pretty. A day trip to Aberdeen, followed by a drive to Edinburgh via Dundee and St. Andrews. A day trip from Edinburgh to ruined abbeys (Melrose and Jedburgh, well worth a visit), and then we got rid of the car in Edinburgh and did that city on foot. (Our B&B was on Glengyle Terrace, a reasonable walk from the Royal Mile.)
Scotland was a fun country to drive in. It took me a day or so to get comfortable with roundabouts, driving on the left and using a gearshift with my left hand (I drive a manual at home, but with the right hand obviously
) but having a car was really convenient. We could stop anywhere we liked.
One photographic downside is that the roads seldom have shoulders, so stopping on the side of the highway to take photos, as we might be inclined to do in Canada, is not much of an option in Scotland.
A few Scottish highways are single track (one lane for both directions). They're not as bad as they sound like they'll be, but they do require careful attention. If you take the drive to Mallaig, you'll drive on a few tens of kilometres of single-track road, and there are quite a few such roads on Skye as well.