The downside to this is the crowds of visitors who arrive in coaches for the grand tour, which is in itself another reason to avoid the popular summer months. You can choose whichever suits your fancy. On each visit I toured by car, which enabled me to cover several areas of the country in all too brief a time. At present the cost of petrol is shockingly high but when divided amongst a foursome it becomes more affordable. Train journeys using a Britrail Pass are a good way to get around if you're uncomfortable driving on the left side of the road in a right hand drive vehicle.
Buses are quite reasonable and their routes link even the smallest towns.
Of course travel by foot or bicycle offers the most inexpensive means to explore. An excellent ferry system provides transportation to the outer isles. I love the ferries, which vary considerably in size and distances navigated. I feel a great sense of freedom standing on deck with the wind blowing through my hair, breathing the clear cool air. A very short ferry ride will carry you to the charming Isle of Iona, the burial place of an-cient Scottish kings.