I agree entirley with Stanbury as we always fly/cruise these days but always book our own flights & transfers, & go a day, or even two, early to see the sights of our departure port wherever it may be. If you've not seen Rome then it's a wonderful opportunity to see one of the worlds great cities without being herded around like a flock of sheep & if you get it right, your airfare, hotel & transfers could work out cheaper than the Celebrity airfare alone.
Yes, indeed, a worthwhile saving as I previously suggested. As a guide (if I recall correctly), Celebrity wanted £230 pp for flights/transfers. It cost my wife and me just under half of that each for our flights, transfers, one night in a (modest but adequate) hotel and evening meal - and we gained a day in Rome. Taking the tour bus (hop on, hop off, ticket valid 24hrs) is a marvellous way to see Rome when one only has a day or so there.
You will almost certainly fly out on same day as cruise starts, but maybe not direct (from Gatwick, I assume) to Rome. As the flight is arranged through Celebrity, you will not miss the ship's sailing if your flight is delayed. But it would be much cheaper and more flexible to arrange your own flights and transfers (coach into Rome, train on to Civitavecchia), ideally going out at least one day earlier with a night (or more) in Rome en route. I did exactly that in July before my Med cruise on Galaxy, flying out Easyjet with an enjoyable 24 hours in Rome before sailing. On the return journey, I had a few more hours sightseeing in Rome, thus avoiding the enforced sojourn at the airport between breakfast-time disembarkation and a flight unlikely to be earlier than late afternoon. Perhaps you should consider cancelling the flight element and making other arrangements to suit you.
For European departures X will always fly you out the same day. Please read the T&Cs 3.1 which clearly states that direct flights are not guarenteed. There have been a lot of complaints on this board recently from people who did not realise this and who's t/a had not explained this to them. If you want direct you book your own flights. To cancel the flights with X if you are worried about routings will cost you £35pp. Personally I always book my own flights, so pick the times I want to travel. With enough research it is easy to find out how to get to the port by yourself, but even with your own flights you can still have the X transfers from FCO at a mere £57pp one way (the train is €12 and €9pp - you can work out which is better value!). Rome is worth seeing, so why not fly out a day early, have a relaxing evening and dinner and enjoy the Dolce Vita?!
Just to put forward an opposite feeling to mix it about a bit..... I often use the cruise line's flights and fly out the same day as the cruise to Rome. We have always been lucky and had direct flights and on most occasions it has cost no more that any other scheduled flight (we will never use budget airlines because there are too many uncertainties with them) and because it is the cruise line's responsibility to get you there have had no worries about that. The transfers are included in that deal so if you are like most of us and take the contents of three wardrobes there is no hassle of having to carry thumping great suitcases on and off trains which can prove tiring and dangerous. I always check my flights as early as possible and if there was a change, say in Frankfurt or similar, I would consider the situation anew. You say you are going in summer and Rome, at that time, can be unbearably hot, most Romans take a very long holiday in August leaving Rome to the desperate and the disparate. The plane is cool, so are the coaches and there is often a welcoming drink as you go onboard. Summer is not a time to be unsure and tired through inexperience, sure you can save money but at what expense?. Hope that hasn't put the cat amongst the pigeons but it had to be said. Most of these guys are well versed in alternatives but if you are not maybe you should think on. Regards ... Neil.
We have always used the X flight option and in January this year, 17th to be exact heading through to Edinburgh aiport the news cam over there had been an incident and Terminal 4 and it was closing for an unspecified time. So we thought how do we get to Sydney now as that was where we were heading to Join Mercury. We phone X and they said they would get us there and on arrival at Edinburgh our flights were changed to go to Frankfurt then Sinapore before the final leg into Sydney, so yes it might be cheaper and despite what some might say they did get us there and on time. So thanks to Celebrity !!