There are around four million acupuncture treatments per year in the UK, of which around half are delivered by members of the British Acupuncture Council. Musculoskeletal pain is the most common condition that patients present with, but traditional acupuncturists see people with a wide range of conditions; mental ill health and infertility are the next most prevalent (Hopton 2012): https://www.ncbi.nlm.nih.gov/pubmed/22240649
The best place to look at the evidence for acupuncture is at Evidence Based Acupuncture. I cannot rate this work highly enough.
You can also find out more via the British Acupuncture Council, who provide a series of fact sheets on a wide range of conditions and include summaries of research and how acupuncture may be beneficial.
Contact me for more information.