Go on get a Jag! The XEs are very nice as well - had one last year. But do consider Avis prestige in Scotland before you book some lesser cars. The roads are lovely to drive on, many with sweeping bends, extraordinary views, and quite a number of single track roads with plenty of passing points. If everyone obeys the protocols there are few problems. Tourists and camper van drivers can be an issue but overall we had no problems (apart from the flat tyre).
We've not completely finished the trip yet but it has been a brilliant journey with fab scenery (although we always take the weather with us and have had 7 days of bright sunshine and clear days around 14-17C).
i may do a trip report on the journey if I have time otherwise I'll pm you on our itinerary and comments when we return to Australia and I have more time. PM me early November if I have forgotten!
Here's a heads up starter
https://www.northcoast500.com/home.aspx