Where, exactly on the AC? Some towns are easier to get to than others. How to get there also depends on whether you go to Rome or somewhere else, like Florence.
I know you didn't ask this, and you haven't said if you've visited Italy before, but I'm going to give an unsolicited opinion about your itinerary. I really think it's too rushed. You only have 3 days in London, at least one of which will be affected by jet lag. You will lose a minimum of half a day every time you change locations. So you've got 1 1/2 days in CT and 1 1/2 days in Rome or ??, then 2 1/2 days somewhere on the AC. If your flight out of Naples is in the morning, you would have to spend the previous night there, further reducing your usable time on the AC. I think your trip would be much less rushed, and more enjoyable if you omit at least one of your destinations. Given that it is high season, I'd recommend cutting CT.