Trading Standards are the various local authority bodies that enforce consumer protection legislation in the United Kingdom. They exist to protect consumers from commercial practices considered unethical or illegal. Originally they were primarily concerned with the area of weights and measures, but nowadays they deal with more diverse issues, such as inaccurate claims or breaches of importing and counterfeit laws. They also deal with what skeptics may call "scams" or the ripping off of consumers, and hence may be helpful with certain causes.
Skeptical activists have, however, have a wide range of success with local TS departments. Some are receptive to reports of false claims or the scamming of vulnerable people, and some seem to lack the teeth to act in the public interest. That being said they are still worth a go if there is something locally that you feel may cross a legal or unethical line - especially in matters of absolutes like false scientific claims. Try to present your evidence in a logical and respectful manner and don't be afraid to politely chase up a case. However, also be aware that many of these departments may be underfunded and their work slow and methodical.
Over the years skeptical activists have enlisted the help of Trading Standards to take on people claiming to cure cancer, dodgy claims from chiropractors, pseudoscientific allergy test services, mind, body and spirit fairs, and campaigns in many other areas.