Well I worked on the assumption that I would do about 40 hours a week including lectures, with probably more around exam time or essay deadlines (the odd all nighter has been known). If you allow say 10 hours a week for lectures, this means you have to do about 4 and a half hours on top of what ever lectures you have each day. It doesnt quite work out like that, as the amount of taught time you have in lectures and seminars will vary each day, maybe even from week to week.
For revision, we had one set of exams at the end of the year and usually about 4 subjects. I *think*, though im not sure, that I used to allow about 6 weeks for revision. That meant roughly 10 days a subject.
I would say though that the time you have is also about quality as much as quantity! Everyone is different as well, so you have to find what works for you too. Hope that gives you a rough idea of what I did tho!