You don’t have to have WiFi service to use iPad. You can use a SIM card from your cell phone on this iPad Air to surf the Internet. You can also connect to the internet without inserting a SIM card from your phone by just using your cellphone as a WiFi hotspot.
Another way to connect to the internet without having a WiFi service is using public places that have WiFi service such as bookstores, coffee shops, Lowe’s, Home Depot, Target, or any Fast food places such as McDonald’s, Burger King, Taco Bell.
I hope this answers some of your questions.