I did that trip a few weekend ago (but from further away Hamilton, not Toronto) in a P90D. Charged at Port Hope and Kingston, and that was enough for me to get to Ottawa.
While in Ottawa, I used my CHAdeMO adapter at the Byward Market (
Clarence St Parking) for a little over an hour for a full charge. They also have a slower EV Plug. I signed up for an account on my phone in 5 minutes while I was there, but if you want to make things go more smoothly, sign up ahead of time at
Electric Circuit's website. You'll have to transfer money to your account via a credit card before commencing. Total cost of charging for me was $20.85.
It was more than enough to get me back to Kingston for the return trip. Otherwise, I only had access to a 120v plug at the friend I was staying at, which was super slow and only good for a very small top-up.
One option I was considering is charging as much as I can on 120v and then heading back via Cornwall, since the supercharger there is closer than Kingston, but it would require a longer over-all trip. I also considered hanging out at MEC because I know there is a good charger there too.
I used the "PlugShare" app on my iPhone to find all the charging locations in Ottawa.
Good luck!