Yep, you have up to a certain period to complete the degree but they will extend that for extenuating circumstances. For any semesters when you are not actively doing subjects, you need to apply for a leave of absence, and there are various acceptable reasons. I've taken leave of absences twice - once for a year when my baby was 3 months old and I realized I just couldn't juggle it all, and once when I was having/recovering from a serious illness when I took 6 months and then an additional year after that. They are more likely to look favorably on your applications if you demonstrate effort during your periods of study, but if you're flakey and drop out of courses and rack up a few fails then they might not approve. This is why it's really important to keep in touch with your course coordinator if you hit any roadbumps.

So I reckon, go for it! If its what you really want to be doing, other things will fall in to place around it. But if you are hesitating because you are doubting if it's what you want, then definitely give it a miss and put that energy into finding what it is you do want.