I went through a kinky phase a while back, so have seen quite a few.
It all depneds on what you want really as they all offer something a little different.
DomStrapon (The clue is in the title) is a really nice lady, very friendly and informal, great with beginners too, so if strap on is your taste, shes great.
Queen of Tease as mentioned in an earlier post, not really a dominatrix in a dungeon type of girl, but really good at sensual domination and has lovely oral skills.
Miss Julia Taylor is a good option, if you want a traditional domination experience, shes based in Dudley in a very well equipped dungeon. Shes a really nice girl too, lots of fun, but you're not likely to get a blowie ha ha, very attractive if youre into thst certain look.
Those are who i'd recommend locally really. All nice characters, and they'll take care of a beginer really well too.