These are links to organisations I know of who provide support and advice on particular issues:
The Samaritans 24 hour helpline for people in distress (Tel 08457 909090)
Mind Helpline for people with mental health problems(Tel 0845 766 0163)
British Association of Counselling & Psychotherapy Membership body for counsellors and psychotherapists. Has searchable database of counsellors in the UK.
United Kingdom Council for Psychotherapy Membership body for psychotherapists. Has searchable database of psychotherapists in the UK.
Spiral Holistic Therapy Centre A range of counsellors, psychotherapists and other practitioners work at Spiral and there is also a low-cost counselling scheme
Re-Vision Runs counselling & psychotherapy training. Can refer you to a counsellor or therapist and also has a low cost counselling scheme
Zhun Arts Runs Qigong and Daoist yoga classes in Islington