Hi Louis!
Nice idea, but I think you'll find UK GA is much too small an arena to try to plant the seed of a new insurance business and grow it without tears. Far too incestuous, far too few actual ultimate risk carriers, and a bit like Ryanair, it's extremely difficult to see how anyone makes a profit.
Remember that the entire UK register of aircraft is less than 20,000 I think, including everything from microlights, balloons and self build helicopters right up to the big stuff owned by BA. Only some of it is GA and as you can't actually become a licensed risk carrier (insurer) unless you have several millions in reserve capital, you'll be relying on the willingness of few there already to pay you part of the usual 20% commission, and even then you have to be licensed as an insurance seller in some way with the FSA.
But if you can spawn something global that hasn't been done before, then that might be a goer!
As for what else you are up against, I once heard (dunno if it is true!) the insurance market was in some years so competitive that one year it cost Lord King more to insure his Roller than it did to insure one of his Jumbos!
While your options are still wide open, and instead of insuring a bunch of hedge-hoppers

, why not set up a hedge fund instead?

- I heard that's where the smart money is
LD