In the States, the group policies negociated by organizations such as the Reserve Officers Association have excellent rates, and have no flying clauses in their policies. I started two such policies while an active test pilot (!) with no rejection. They are "term" policies, which simply pay for death, with no cash value (the only kind of insurance to buy, I think). Almost every professional society has such plans, with similar rates.
I don't know how UK insurance business is run, perhaps this is not a possibility.