The NHS: The NHS is an obvious starting place for people in the United Kingdom. If you think that you might have bipolar or any other mental health issue, please make an appointment with your GP so he or she can refer you on for latter consultation. I would encourage anyone who finds the strength to stand up and ask for help to remember to be proactive on their own behalf – if you can provide data on your ups and downs and various spells, it will help them diagnose you faster and more accurately.
Bipolar UK: A charity dedicated helping people with Bipolar with a range of services (and an e-community if that’s your sort of thing).
Mind: Another charity with lots of good advice, information, and help.