UofT schedules your classes for you from Monday - Wednesday, and has you at placement Thursday and Friday. This was in last years MSW handbook, and they mention that exceptions can be made pending approval and stuff
From what I've heard UofT isn't the most flexible with full-time and mature students, but if you took to the right people maybe you can be accommodated for.
I know other schools will allow you to do your placement in a block format (which sounds like what you'd like to do by taking a leave of absence), as well as schedule your own classes in the afternoon/ evening.
I applied at UofT as well, but I also live in Toronto, pay rent, and work full-time. I did my entire BSW and placement while working full time and it was possible because of the flexibility of the BSW program at York, but I'm not sure how that's going to look during an MSW.