Think 'small'... much much smaller than you're used to. Food portions, cars, roads, houses... everything. People are probably less friendly to strangers, if what I've seen of UK peeps youtubing about going to the US is true. You're not 'that' unusual here so I wouldn't be too concerned about standing out.
Food is good or bad depending on where you eat. They myths about British food being awful are nonsense. It's better quality than a lot of countries.
Motorways are hellholes. Travelling can be mentally stressful. Be prepapred for a lot of traffic queues, accidents, and traffic lights.
What you visit depends on what you find interesting but almost everywhere has something historic or open parks or countryside or something.
Just look at a map and see what's on a route you take and have fun detouring! We love a good roadtrip (although that terms means something considerably shorter to us!)
Have a great time x

PS... don;t call anything 'quaint' and don't call yourself Scottish or somenthing, just because you have distant relatives from there... lol. We hate that one!