"....We're flying to Italy so long haul flights have to be there 1 hr beforehand according to their site...."
Are you saying you're flying from Gatwick to Italy? If so, that isn't long haul it's short haul so you really only need to be there an hour before. However, as has been pointed out previously, that time of day is very busy with many package holiday flights so I would aim to be there two hours in advance. You'll be tired but less stressed!
Oh and stay at the airport the night before, far less stressful than trying to get from London.
I've pretty much given up on early morning flights, particularly when it comes to holidays. They're supposed to be relaxing so if I can get an afternoon flight I'll take it, get to the airport with plenty of time to spare and relax in the lounge. It may be more expensive but it's worth it to avoid all the stress.