Hiya
I don't know if you are still looking for info but your post just popped up in a search.
If you draw a circle encompassing Stalbridge, Dorchester and Beaminster then you should be within a 40 minute commute taking rush hour traffic into account.
I lived in Sherborne until I wanted to buy my own house and couldn't afford one so hopped over the border to Yeovil and have lived here for the last 14 years. People will say a lot of bad things about Yeovil but actually there is a lot to be positive about as well.
Yeovil is the largest town in the area and has a great range of facilites ie groups, clubs, cinema, swimming pool, shopping. It also has a reasonable public transport network and easy access to the A303 which gets you to the M5 or M3 relatively easily. The local council is working hard to improve the town and frankly I think it's working. Yeovil has a lot going for it. The schools are mostly achieving well and house prices are less extreme than in Dorset.
Sherborne is a lovely market town with a good selection of independent shops. The primary schools have good reputations and the comprehensive is rated outstanding but it is now huge relative to other schools in the area. Housing is relatively expensive with even the less desirable areas achieving good prices.
Dorchester is not popular these days and the local council have made some questionnable decisions which some would argue have contributed to a general decline in the town. I have worked there but not lived there so couldn't comment any further.
There are lots of nice villages and many have a primary school, pub and shop. Most children take a school bus to access secondary school. Public transport around here is expensive and infrequent outside of the towns. Access to and from villages can be troublesome in the winter periods and flooding of roads is a particular issue around here. Also remember that the further away from the main roads you go, the narrower and twistier the roads become adding time to your commute. Many of the villages make good use of their village halls to provide clubs like Brownies and Cubs, ballet, football but it really does vary from village to village.
If I were you, I would consider the things that you really don't want to lose when you move and the things you would most like to gain and see if you can strike a balance. Look at the facilities that the villages offer and remember to consider the downsides of village life (distance to supermarket!) as well as the positives (the beautiful country air miles of green fields and footpaths). There are many villages lying on the outskirts of the above towns which might offer a compromise.
I hope that's of some help. Good luck with whatever you choose to do.