I have to say that I found it impossible to work a part-time job at the start of the course, unless your hours are extremely flexible (as in being able to call up and say when you can work). I kept working on Sundays for a month or so, but as continuous assessment began to pop up on the Mondays I had to give up entirely.
I'd like to have some kind of income during the course, but I eventually accepted that I was going to be in debt by the end of it. It's not so much the lecture hours that I found difficult to manage my time around, but the amount of library / revision time to keep yourself from falling behind. I also wanted to be able to spend time with my class and non-med friends outside of study time, so I didn't want work affecting that either. So like I said, maybe with good time management you could fit in some part time work.
As for getting married and such .. I haven't really considered it since I'm on the younger side of the GEP age groups. You still get holidays, so I'm sure it'd be do-able. The organisation could take quite a lot of time management though. Like yazoo said, it'd certainly be easier to plan during med school than during your Junior years
Don't let this discourage you - it's a serious commitment, but it's definitely worthwhile.