Insurances have an unhappy knack of defining disability as TOTAL ,not what people may reasonably say is total,nor indeed do they readily payout on permanent disability with which you are diagnosed.
On things as clear cut as Heart Attack or a lot of cancers, it is becoming very hard to get claims through.
If your policy is a PPI Type product ,I would be afraid for you as their payout exclusions are sadly too well known .
Get a copy of actual policy and really read it to see where you are.
Wish you luck.