I know why I don't have guide data for Pluto TV UK.
To set up my Pluto TV source, I used the @KineticMan version:
Unfortunately, there are playlists only for all or local regions.
After creating the original source for the local region (using the OliveTin Project One-Click action), I manually created the source for the UK region by duplicating the local URL and replaced "local" with "uk".
The video streams actually work but there is no XML file generated for the EPG.
Question for @KineticMan: it seems that the streams exist by simply replacing "local" with "uk" in the URL. Do you think EPG could be generated too?