Not much there pal, you'd be better of going to Bristol as that's about 40 minutes away but as for who to see the only ladies I've seen in Bristol are the ladies below
First two are excellent and two of the best I've seen but book up extremely quickly.
External Link/Members OnlyExternal Link/Members OnlyThe below is there 26th and 27th ( she's also very good but a bit pricey and has bolt ons, they are very nice though )
External Link/Members OnlyThis one is Exeter which is around the same distance in the opposite direction but is out call only, she will travel to you for a fee which could work for you if you have a Hotel. Haven't met her yet personally but in the process of trying to sort something out with her and she does have a couple glowing reports on here.
External Link/Members OnlyThese two I have seen but the first one I didn't rate but lots of others did and the last one used to be awesome but nowadays seems to be on the decline along with her reviews as of late.
External Link/Members Only. She's primarily Taunton which isn't far at all from you.
External Link/Members Only She's also Bristol, ( bolt ons ) been tempted to try again but been put off by all the negs as of late.
That's all I've got I'm afraid as the South West doesn't have a great selection at least not the area you are talking about. Sure some of the other guys can add to this list. Oh and all of those are below forty.
Good luck