The British Dental Association is the main professional association for dentists in the UK, with a membership of in excess of 18,000 members, the majority of the profession. Their is a public information area on the website where patients can access information about various treatments.
The General Dental Council is the organisation which regulates dental professionals in the UK. All dentists, hygienists, therapists, dental nurses and dental technicians must be registered to work in the UK.
The British Dental Health Foundation is a charity dedicated to raising public awareness of dental and oral health. Again, the BDHF site is very patient focused with lots of independent and useful information.