I would recommend you treat this as two transactions. Get a cheap flight to FCO or CIA, but consider flexibility in the ticketing in case you want to go a day earlier (bad weather etc). I presume this is Civitavecchia - note it is 50 km from FCO and 70 from CIA. The travel to a ship and from a ship have two separate factors and it's best not to confuse them - factors such as weather, late docking. There's a different degree of flexibility needed on both sides. If you end up in Red Hook at the NYC end, you don't want an EWR service if you can avoid it (though if it's Cunard they do put on coaches to EWR, LGA and JFK). For the USA-UK then yes use the 2-4-1 to go Club or First - I would book whatever you can now, and since it's standalone one-way it's easier to control, for example if a better flight or cabin becomes available. Consider also Iberia and Aer Lingus options if using Avios, they can sometimes be a lot cheaper for the indirect routing.