It normaly is always cheaper doing your own flights, but we have always taken the view if we are spending £4k what is a saving of around £150/200 on the trip. You will have to get to the ship on arrival and the sae taxi option on the return trip. If for any reason your flight is delayed the cruise company have no responsibility, well this year we were flying out to join the Mercury in Sydney and it was the day they closed Terminal 4 at Heathrow so when we arrived at Edinburgh airport we thought we were going nowhere but arrangements were already in hand to fly us to Frankfurt and then onto Singapore where we met up with the flight we were due to leave on and landed in Sydney on time and much to the surprise of the reps at the airport.