Cotswolds in December

My wife and I are planning a trip to the UK on December. A few days in London, then Bath, and want to spend a day or two in the Cotswolds area. What we're wondering is where in the cotswolds would be a good home base, and what is the easiest way to explore several towns? We will not have a car, and from what I have researched, there are not many tours running that time of year. Any suggestions would be appreciated.