Maryrff.. Feel free to phone if you need to. You may have found a long distance bus to get there, but you will be marooned there without a car. Local busses usually run only during the daytime, every two hours as a guide, and not at all on Sundays. So pre-booking somewhere to stay within walking distance is a good idea, although hitching is possible but not reliable. I'd suggest you visit the Tor, the Well, the Rural Life Museum and the Abbey, if you have time, and also try our cider (small quantities recommended at first) - ask for 'Farmhouse' in the smaller, scruffier pubs for the real thing (if you're lucky), plus proper Cheddar cheese (again 'Farmhouse' and 'Rinded') and Lardy Cake.
Oh, and feast your ears on a local accent if you hear one (still quite common, though losing strength and depth of accent) - this is how 'folk' song used to sound when it was collected by Cecil Sharp 100 years ago.