Even when you did need a dentist, medieval people were a lot more travelled than you might expect. Even abroad thanks to the crusades.
Some of them, yes, but not usually at will unless they were wealthy. For example, a sailor on a merchant's trading ship might be well travelled, even abroad (there was a lot of international trade), but they wouldn't be travelling where they chose when they chose. Although they might well get some time spare in a trading port, which would probably be at least a fair sized town (by the standards of the time, when a few thousand people was a big city) with a dentist.
The average person could probably spare a couple of days to travel to and from the nearest town with a dentist and a serf would probably be allowed to leave their lord's manor for it. An average person, free or serf, might even live close enough to walk there, get treated and walk back in a day. But even so, it would still be true that "dentistry in medieval England was hardly impressive and prevention was a far better option."
And there were also travelling fairs that might have a dentist with them.
True, but how often would one be stopping at or near your village?
Of course medieval dentists were very different today - pricey and quite gleeful about ripping out your teeth and leaving you in agony...
Maybe, although it would be better for their business to not do so. A dentist who could pull teeth efficiently and with as little pain as possible could charge more and would probably get more work too. People tend to prefer to be good at their trade, anyway. But medical knowledge in medieval England (or anywhere else at the time) was quite limited. There would be a risk of infection and treatments to prevent or treat it were of limited effectiveness. Also, as you say, cost was a factor. Pay for the dentist, probably pay for somewhere to stay overnight, probably pay for some sort of aftercare product that you hope will prevent infection (and might - some plants do have antibacterial properties)...it was coin you would probably prefer to spend on something else (assuming you had they money). Oh, and pay for the booze to get drunk enough to dull the pain
There might be other forms of painkiller available, but alcohol would probably be cheaper and safer.
I think prevention was definitely a better option. Pass the hazel twigs, please