Can't help you with the regs where you are, but a couple of things I've discovered:
The heliport will be very, very tight. When they tell you "No worries, it's the world's largest tanker", don't believe it. Ship size has nothing to do with heliport size. I've landed very close beside a prop stored on deck, much larger than an S76. In any case, the clear area will be barely enough, with all sorts of pipes, cranes and other odd masses of steel. Make your approach very, very slow, and always be prepared and able to go around.
Practice your slope landings. The decks have a pronounced slope. Not dangerous unless you release the brakes, but do not do that.
Watch out for the ship turning while you're on the deck. The crosswind you landed with can become a tailwind before you're ready to take off.
No matter what the ship's captain says, he can turn it for you so you can get a favorable wind, especially if you have his relief on board and threaten to return to shore.