Check easyJet and Ryanair anyway - just factor in the baggage charge when comparing the prices. I certainly recommend the former - I use them twice a week at the moment and have done extensively in the past and I find them generally reliable and the crews friendly (particularly those based at LTN, but I only recall having a miserable crew once), and the prices usually good as well.

You also get to avoid Heathrow - EZY fly to Gatwick from Rome. Unfortunately not Luton, though, which is one of the better London airports to use in terms of getting through quickly, though admittedly it's a long way out of London.

Neil