After the now-legendary Ash Disruptions of April 2010, train travel across Europe seems an even more attractive prospect. The ongoing threat of flight cancellations (today several Italian airports are closed as a volcanic ash cloud drifts by), ever-increasing airport security hassles and environmental considerations are enough to make many travellers consider alternative options.
Thanks to Eurostar and the Channel Tunnel, you can travel all the way from the UK to Italy by train, changing trains and stations in Paris. It is actually possible to make the journey in one day, though if you're enamoured of the romance of rail travel, you may prefer more leisurely progress with an overnight in Paris, Switzerland or northern Italy.
It's not even that much more expensive than flights, if you book ahead. I found a €45 ticket on an overnight train from Venice to Paris, and a £45.50 single ticket on the Eurostar from Paris to London. So I could have left Venice in the evening and reached London by lunchtime, for a cost of around £85. You don't get a view from overnight trains, of course, and I was rather daunted at the default option for a shared couchette being 'promiscuo' (happily, the drop down menu did give the second option 'donne', women). So I chose a two-day journey with breaks in Milan (overnight) and Paris (several hours in the afternoon), for a combined cost of £160 including a hotel and first-class travel between Milan and Paris.
You can read more about the various options for travelling to Italy, with routes and timings for different Italian cities, on my new page Travel by train to Italy.