Try Harborfront Canoe and Kayak Center. They are at Queens Quay They provide courses as well as boats.
http://www.paddletoronto.com/kayaking.htm You can rent a decent touring boat (wilderness systems) and go to the Toronto islands. It's a fun trip. If you are afirst time paddler you can go to Kelso concervation area in Milton. Very flat lake and boats always available Cheers