Use those 4 hour gaps wisely, I'm living at home too and will be using gaps in between lectures to get work done so that I can have my evenings free (or at least, slightly more free than if I were to be doing everything after uni). You're doing a full time course, but that doesn't mean you'll be in lectures 40 hours a week. University is all about independent study, although you may only have a few contact hours a week you should still be treating it pretty much like a full time job.