The British Association for Counselling and Psychotherapy has lots of information on different types of therapy as well as a members list of therapists. This is one of the governing bodies for counselling and all therapists registered adhere to a code of conduct.
College of Sex and Relationship Therapies are similar to the BACP but they specialise in relationship therapy and have their own code of conduct for therapists to adhere to. My master's degree is accredited by CoSRT.
The National Autistic Society have a website with lots of information about Autism including advice, guidance and online support.
BEAT are one of the UK's leading eating disorder charities. This website has lots of information on the subject as well as downloadable resources to support you. They also have helplines and chatrooms available.
This is a great website for those who enjoy things loud and shouty! They have great resources about diagnoses and also run support groups both online and in person.