We tried to always carry a spare meal for the evening, even if we didn’t plan to eat it. Mostly used pre cooked curry’s that were in bags which we could just heat up, saved us on more than one night.
I think we share the same regret as you, not having planned in enough time to see the things we didn’t know about, like small town you pass through or castles you didn’t know existed.
I think the next trip will be north, round the Highlands a bit and up to Thurso. Planning it for a much slower pace so we can take time to see things and because of the hills.
I really hope in the next few years we see a revolution in short distance transport. Most journeys are less than 3 miles (if I remember correctly, could be 5) a perfect distance for e-bikes, e-scooters and normal acoustic bikes. Hopefully at least some places capitalise on it