Everything I read (specifically: http://9to5mac.com/2014/09/23/peer-to-peer-airplay-apple-tv-ios-8/) states that the Apple TV A1469 running Apple TV Software version 7 and newer offers Wi-Fi Direct (aka peer-to-peer Wi-Fi) connectivity for Apple devices running iOS version 8 and newer so that AirPlay can be used without either device being connected to an access point.
This is almost exactly the setup that my family has - an Apple TV A1469 running the newest Apple TV Software version 7.0.3 (6917) and an assortment of iDevices (iPhone 6 Plus, iPhone 6, iPad Air, iPhone 5, etc) which all run iOS version 8.1 and newer.
However, none of these iDevices are able to utilise Wi-Fi Direct - AirPlay will only display if the Apple TV and iDevice are both connected to the same Wi-Fi network. See below for evidence of this.
Apple TV connected to the "Wiffy [2.4GHz]" Wi-Fi network:
iPhone 6 connected to the "Wiffy [2.4GHz]" Wi-Fi network:
AirPlay available on the iPhone 6 to the Apple TV, both connected to the "Wiffy [2.4GHz]" Wi-Fi network:
Apple TV disconnected from all Wi-Fi networks:
AirPlay not available on the iPhone 6:
Apple TV current software version:
Apple TV software up-to-date:
iPhone 6 current software version: