The Samaritans are available 24/7 in the UK at 116 123. If you could use someone to talk to right now, don’t be shy about giving them a free call.
The British Association of Counselling and Psychotherapy offer useful information on how to find a therapist and as well as what you might expect from talking therapy.
Mind are a mental health charity that ‘provide advice and support to empower anyone experiencing a mental health problem.’ Visit their website to see what they offer in your area.
YoungMinds are a mental health charity for young people, and offers support for parents and professionals as well as young people themselves.
Not OK was developed by a teenage techie for his sister, so that she wouldn't be shy about reaching out when she was feeling low.
I had a Black Dog. His Name was Depression by Matthew Johnstone. A great book turned into a video by the World Health Organization.
Self-Help for Trauma offers free relaxation techniques developed for survivors of war and other atrocities.