I did exactly that transition after getting very bored of fixed wing (ooooh, can of worms!
) earlier this year, and as Bravo says, it's two exams plus the flying hours.
For me, doing the (A) course beforehand was an unintentional, lucked-out smart move. It meant I didn't have to burn expensive flying hours learning nav, airmanship and radio. Spending £3 a minute learning those skills would have been a bit of a dent in the old budget I could have done without.
When it comes to fun factor, well put it this way. I never wanted to take the fixed wing stuff to a 'getting paid for it' level, but the (H), I definately do.
All I can say is go for it, and good luck.
