Fiat are not actually that bad at getting cars built & shipped quickly. Standard wait is around 12 weeks, which is a hell of a lot quicker than the likes of VW, who have had people waiting since August last year for Scirocco's.
I belive from leaving Italy, the boat trip is about a week, then they can spend a week at the Port in Bristol, as they seem to wait to get a completely full transporter going to one area of the country before setting off. Understandable given the cost of fuel.
I reckon if it's on the boat you'll have it in around 2 weeks.