If you connect your iPad to free Wi-Fi (such as at coffee shops, airports and some hotels) when you're in Canada, you can check email or otherwise do things online without added cost.
If you have an iPad with cellular data, you'll likely have to pay for data you use in Canada when not on Wi-Fi. This depends on your cellular provider, though. T-Mobile offers free basic data on tablets when traveling, but others usually want you to pay for international data plans. My suggestion: unless you need email wherever you are on your trip, it's easier to just wait until you can connect to Wi-Fi.