There are two apps for Plex. One is free but needs Plex pass which you have. The other is a paid app that doesnt need Plex pass. It's a one off purchase so if you ditch your pass then you need to pay for the other app. After then it's free to use.
In regards to iPlayer I was talking about pushing programmes from your PC's web browser iPlayer rather than the iPlayer app found in iOS and Android.
Plex just updated the Android app.
thanks for that, will keep my plex pass as other family members connect to my server and use the android app.
@rogan
to add to my reply above, you can cast from plex via chrome on your laptop if wanted.