This trip (stonehenge, bath, cotwolds, stratford) is a long one that does not include any food with the ticket price, so you will want to pick up some food at every opportunity. Our tour ran on an Sunday, so many of the food places and shops closed early by the time we got to Stratford. Our guide Omar was fantastic, very knowledgeable and passionate about the subject matter.
I do think that it was sufficient to do all this in one day (Cotswolds is more of a drive-through anyways, you do not actually get off the bus for that one). Maybe Bath you could spend a whole day exploring the town, but we were satisified with the few hours we spent there.
While all of this was made very clear in the trip description before purchasing, I wanted to reinforce that there are upgrades not included in the ticket price, such as entering the Roman baths. This was probably the coolest part of the trip, so I recommend paying the couple of pounds needed to do this upgrade.
I was personally underwhelmed by Stonehenge as I did not realize how few stones are left and they were all covered in moss and decay. However, Stonehenge is actually just one of MANY monuments nearby, and it is not the oldest by far! Several burial mounds and other monuments are also there that were interesting to learn about. The visitor center of Stonehenge has a "virtual reality" wall projection video that shows what Stonehenge used to look like when it was first built through time and different weather/seasons. Omar took us to see it and explained what each part of the projection video was showing, which I really appreciated because I would not have realized what I was looking at without his explanation (such as that on the solstices, the sun would rise in between two stones, only one of which is still standing now).
Full disclosure I was asleep when we drove through the Cotswolds; it is a lot of bus time because of how many attractions you are cramming into one day, and many people nap on the bus anyways.
Shakespeare's school house was interesting, the people who work there are very enthusiastic about the history and the town itself is a cute tudor style location.