It really depends on the course you pick. We don't have much contact time so most of our work has to be done in the masses of free time we get, and again that depends on your organisational skills and motivation. I have a part time job, I row with the local city club at the weekends, I go to extra lectures organised by the medical societies here most Tuesday, Wednesday and Thursday evenings. I go into schools with the Widening Access to Medical School team to lead classes telling people they can be Dr's too, and I go into schools and teach sex ed with Sexpression. I have between 15 and 17 hours of contact time a week depending on whether it's week 1 or 2 in the timetable. I couldn't row with the uni because they wanted three water sessions and 3 land based training sessions a week and I couldn't give them that much time, but I'm having just as much fun with the local team (and it's easier to win races because the competition is tough, but not as fierce) and it's a lot cheaper and more relaxed. If you really want to do it, you can find time to fit it all in, especially in your first couple of years.