I have Bipolar Type II, will I get a visa?

I have Bipolar Disorder Type II, which does not include psychosis as a symptom. I take medication for this. The Visa application asks about 'severe mental distress', so I assume I need to declare my illness. Will I be automatically turned down for a Visa because of this? I don't want to spend a lot of money on flights and the Visa application if there's no chance of being allowed into the country. (I'm British, if that makes a difference).