Janet,
We spent 28 days driving around S. Wales and England in October 2017. It was a wonderful trip.
We visited Stonehenge and Salisbury in 2013 on our first time driving on the left. We did Avebury in addition to Stonehenge and Salisbury in one day. Loved visiting the Cathedral after reading Pillars of the Earth by Ken Follett.
In 2017 we stayed in Bath for three nights and also did a day trip to Wells and Glastonbury that was nice.
We did six nights at the Volunteer Inn in Chipping Campden. The room was spacious with lots of windows and had a good bathroom. The small hotel has a great pub as well as a great Indian restaurant. While there, we did a day and a half touring the Cotswolds. Make sure you check out Rick Steves Great Britain guide for doing a day at the Cotswolds.
Also, we did day trips to Oxford, Blenheim Palace and Stratford Upon Avon (loved that city). We had been in country for 11 days, so on our last day there, we did our laundry at Moreton-on-Marsh. Also, that is were we took the train in to Oxford.
While in Stratford Upon Avon, go to the Shakespeare birth place, which has a nice small museum and buy the ticket for five sites. Be sure to go to all. We used the HoHo bus to get to all five.
If you aren't used to driving on the left, I recommend you get a nav system in the vehicle as well as an automatic.
Also, driving through those little towns in Britain, when it says 30 MPH, they mean it and have cameras. I tried to stick to the speed limit, but got a 40 pound ticket for going 35 MPH.