Driving through English Countryside

You have a reasonable basic plan. But honestly, put all the places you want to see on a map and see which bits you can reasonably do. All of them is only possible if you drive a lot, every single day!

Or use a month.

Or plan another trip in the future for the things you can't see this time.

You could be spending a lot of time in the car and not much at the locations. A full study of a map with the locations and roads will help you see how much needs to be eliminated.