Yeah it's mostly pot luck with the tourers, just look at who is touring on Adultwork and check each of them on here for reviews.
Bella 31 is in Coventry most of the time (although I think she is still a tourer), so she's probably the best you'll get. She is good VFM, early 30s, slim with big tits, friendly and good service at a low cost.
There's the Paradise Girls whorehouse in the north of the city but most of their women are either old or fat. I'd recommend Alyssa who works there three days a week if you're going to go there, but she's on the chubbier side.