1 dog groomer listed in Castell-nedd Port Talbot. They are based in and around Ammanford.
Dog grooming is not a licensed trade in the UK: there is no council licence and no register, so anyone can set up. That makes the questions you ask more important, not less. Ask what qualifications they hold, whether they are insured, and how they handle a dog who will not settle.
Ask to see where the dogs are kept while they wait, and whether yours would be left in a cage to dry. If your dog is nervous, elderly or matted, say so when you book rather than on arrival: a good groomer will want to know, and may suggest a shorter first session.