Both Alitalia and British Airways offer daily flights. Cut-price flights are available from London Stansted with Go .
Prices vary dramatically according to season and type of ticket - shop around for the best deal.
Unless you loath flying, competitive air fares make the train journey really only worthwhile when combined with a cut-price rail pass allowing further travel within Italy. If you are under 26 or a senior citizen there are further tempting discounts - enquire at a main railway station for details. If you want to take your own car to Italy but can't face the drive, you might consider using one of the express car sleepers - expensive but a good option if time is short and you want to carry mounds of luggage, children, tents, etc. For more try the Italian State Railways site. If you are this desperate, hitch a lift with a long-distance lorry driver.