Bae
You would probably need the triple guys/girls to help here, since that's probably where you would end up as a DEPs, as I'm on the 747 I can only give one point of view. It should be a minimum of two days off, it will sometimes be more. Also bear in mind some of the three day trips have early reports, meaning you may have to commute to London the night before, on the other hand many of them also have early finishes ( e.g. getting in from the States breakfast time), so as long as your commute is fairly efficient you could get a fair proportion of day three of the trip actually at home - swings and roundabouts and all that.