OK so the quickest way to get Netflix working is to download the APK from here https://www.apkmirror.com/apk/netflix-inc/netflix-for-android-tv/netflix-2-1-build-425-android-apk-d... copy it to a USB stick and insert it into the TV. 

Goto https://play.google.com/store/apps/details?id=com.estrongs.android.pop and tell it to install to your TV (make sure you're logged into your google account on the TV). 

You'll need to make sure you allow installs from "Unknown Sources" which is under Settings > Security & Restrictions

On ES File Explorer on your TV navigate down to your USB stick (left hand side, just keep pressing down) and then click on the APK, then on Install. 

Load up netflix and sign in / up

Enjoy the 4K goodness