In reply to benjied:
When I was getting quotes from my broker at the same time as my mortgage I made the mistake in telling him that I "occasionally went climbing and caving" and it sent my premiums through the roof. My broker advised that if it wasn't something I was doing more than a couple times a year just to leave it off. So I did and then promptly advised my pals if I was to snuff it doing either activities to drag me out into the road and run me over just to be on the safe side.
But back to topic, re: the bipolar, it's not uncommon for them to hike the prices up, might be worth skimming through this and seeing if any of it is relevant:
https://www.mind.org.uk/information-support/guides-to-support-and-services/...
EDIT: Also a list of specialist insurers, you might find they are more fair
https://www.mind.org.uk/information-support/guides-to-support-and-services/...
Post edited at 12:03