There are day tours and multi day tours from Edinburgh. A car is ideal(that’s what we did when we were in Scotland) but husband was driving. There are trains as well to other cities.
My sister and I would have had to rely on tours from the city when we visited Iceland a few years ago. We would have been too nervous to drive ourselves. One of my sons ended up coming along though and we ended up renting a car , and he did the driving!