I have not been to the south west,the only thing i can suggest is try Adultwork,if you are not a member sign in.Go on search at the top of the screen,type in escort,female,incall,Region South West and Area/County Somerset,and other area's close to you,then on the far right tick BDSM & Domination,then press search at the bottom right of the page.
I tried it for just Somerset and 34 girls profiles came up.You will know other area's close to you,i don't.
It's the best i can do.