As an Italian, I can tell you that you will not have particular problems in the big touristic cities (Venice, Florence etc.) when dealing with touristic operators etc, but if you want to communicate with common people and especially in “rural Italy”…well, that’s another story.
From direct experience I can tell you that in Italian school they usually teach foreign languages in a poor way: they are too focused on grammar and they don’t encourage speaking and the learning of vocabulary. So yeah, people might have studied English at school, but at the end of the day they don’t actually speak it.
Those above who say 80% Italians speak English are WAY too optimistic: the majority of Italian people are old and no, they do not speak English.
If you’ll come to Italy and visit also rural areas and you’ll need info, I highly recommend you to ask young people. There are several of them who know English thanks to the Internet.