I found it pretty hard to find any decent information about where to paddle in Toronto on the East Side. I think I'll try to share what I learned, eventually, over time. Everybody hates a web thing that evaporates, I know - so I'll state at the outset that I'm new to paddling and not adventurous. I'm quite happy to get to know the area I know, and save moving on for later. Like a character in Wind in the Willows or something, the stodgy one. So if you're looking for action, move along.
I paddle from Cherry Beach. It isn't far to walk from the parking lot to the water, and you will have to carry your kayak (or get a little cart). It's a really nice place to learn to paddle: its in a little bay, and so if you want to avoid harbour sized waves while you're learning, this is pretty still water.
Lots of people launch from this beach; be careful to go to the outside of the swimming area, the lifeguarded bits; the far end of the parking lot is great.
You can hug the shore and do quite a nice route. I do this in the late Fall and early Spring, because I don't have a drysuit, so I can't go into any depth. It's a pretty route (if you like the Toronto shoreline mix of nature and construction refuse, which I do).
In the map below I cut across the bay at the end, and that's about 10 km. [continued below]
The whole area surrounded by the red line in my map is super calm. Easy paddling, and really beautiful; you'll pass a couple marinas, and the Hearn. You can use this route in the colder months, as it's shallow (I did this in summer, so cutting across the bay was safe). The Paddle Logger app I use is great, btw, for simple uses like tracking routes It's free. Just remember to turn it off before you leave, or you'll log a speed of 46 km/h, which is hard to maintain.
What else for now? The Complete Paddler is a great shop, and, not being MEC, they'll talk to you for a long time about paddling. (Not meaning to dis Mountain Equipment Coop - they are great, and they're where I bought most of my gear originally). But I like the little guy by nature, and TCP has a community thing; they have group paddles all the time, classes, and last year, a film festival. Not being one of those community people, I do not partake in most, but I took one of their courses in the winter (on doing a self-rescue with a paddle float) and it was great. They're really nice people and know what they're talking about.
I'll try and share a bit later about weather, gear, other places to launch. All from a beginner's place. Just so you can find it on the internets.