Group Policy is a tool for controlling the settings on a large group of people, such as enforcing that everyone's wallpaper is the same picture at a school or business network. Since it's designed for those, it's only included in the business and professional versions of Windows. The home and basic versions don't have it. Think of it just like a car: there's the base model, then the more expensive add-one you can buy.
Luckily just because the little tool isn't there, doesn't mean you can't accomplish the same thing. The How-To-Geek explains here: http://www.howtogeek.com/134620/how-to-disable-the-lock-screen-on-windows-8-without-using-group-policy/