The following two links show you all tennis courts available in the Ottawa areas.
City of Ottawa - Tennis Courts - East
City of Ottawa - Tennis Courts - West
You can buy a junior racqect from any sport stores. The regular racqet is long about 27 (or 27.5) inch, junior racqect with a size of 25, 23, and 21 inch depending on age and height. The taller, the stronger, the longer would be fine. Do not buy any extend long racqects (e.g. 28 inch or longer), which could cause tennis elbow. I have two junior racqets, 21 and 25 inch long. You can let your kid try if you like. Good luck!