Solo September in the Cotswolds

This is a very partial answer, because my experience in that area is limited.

You can't use trains to move around the Cotswolds because there aren't any. Moreton-in-Marsh has a train station (with good service from Oxford). The smaller places in the Cotswolds--the ones you'll see recommended if you search earlier threads on this forum--have no rail service. Bus service seems to be very limited. I think Moreton is something of a bus hub, so it would probably be the best place to stay without a car. A further advantage is that if you wake up to dreadful weather, you can hop on a train to Oxford and enjoy the indoor sights.

There is at least one company (GoCotswolds) running one-day small-group tours out of Moreton. I took one a few hears ago while staying in Oxford. I found it enjoyable and a very good way to see a bunch of small villages in one day.

My suggestion is to consider taking one of those tours so you can cover a lot of ground without worrying about transportation. Then plan another day or two for walking. My guess is that you'll be able to get from Moreton to the starting point of a walk by bus but will have considerable difficulty traveling between little villages by bus. And you might well need to pre-arrange a taxi to get back to Moreton at the end of the day.

Yes, renting a car would be easier--if only you didn't have to drive it.

I have been to the Cotswolds 3 times and never rented a car. Our first trip there, we used one of several companies out there to book various B&B’s in the region along with baggage transfer to each B&B along the way. It worked fine. We found that we prefer finding a nice base for 5 or more nights instead of packing/unpacking every night. Although bus service can be limited, there were enough routes available that worked for us when needed. And, don’t forget that there are taxis in the area. Typically, we would call for a taxi in the morning to take us to the start of our planned hike for the day. After a day of hiking and drinking some real ale, we were usually successful in taking the bus back to our town. If the buses were running a limited schedule or we didn’t like the timing or length of the route, we hit the pub for a couple beers and the bartender called a taxi for us to head back. We based in Stow-On-The-Wold and enjoyed it thoroughly.

Thank you Jay MN and acraven for your insights and ideas. I have found a few day-trips from London, which look pretty darn good, but I am greatly encouraged by your description, Jay! Thank you! I'll keep researching. :)

I wouldn't want to do a day trip from London if all the transport was by bus. There wouldn't be much time left to see the Cotswolds. I think Lonion Walks may occasionally do a Cotswolds trip that does the long-distance transport by train.