Wanting to use wifi not cell on iPad air 2. Function like the iPhone.

I want my wifi to take lead on my cell enabled iPad Air 2 the way it does on iPhone. While at home I want it to use wifi not cell. I know I can disable cell on iPad but that is a redundant step and not sure why cell would ever take precedent over wifi Any way the iPad could function the way the phone does? Much cheaper to run Internet at home with wifi and it's frustrating to have to remember to turn cell off when at home, which it's easy to rack up huge useage totals. Any direction and/or updates to this would be amazing!