Much of Europe has an age restriction for car rentals. I think Scotland was 75 when we went there some years ago.
This is not a bad rule as country driving and roundabouts are a different world. When you add in turnouts and massive tandem lumber trucks with bogs either side of you, good luck! I was used to stick and clutch cars so that was not a problem. Loved driving the smaller cars but pack lightly!
More thoughts, in Edenborough, the National Museum of Art is wonderful with lots of heroic 19th C. Art. It's not unusual to see Street performers in this area as well. The original Department Store can be a fun trip especially when you eat their as well. Poets and performers make Scotland a joy. Develop a brough.
Get a haircut, the barbers seem to care about their craft. Glasglow's man shopping area is wonderful. While there, visit the McEntire Tea shop for scones. Enjoy the furniture in the tea shop for it's amazing Arts and Crafts style of this 19th C. designer.
Visit during heather blooming season, early to late fall. Bring rain gear and sweaters or buy them there. Enjoy. The folks are wonderful and the sight lines, while driving, are beyond compare. Bring English coins to feed the meters in the cities. This is critical. Meter maids do their jobs.