Access to the Dinorwic Slate Quarries will be limited for 7 days or so from the 11th June (or for a 7 day period from up to 6 months of that date). Filming will take place for the new Tarzan film, a notice at Bus Stop Quarry states that access will be limited to the main track from Bus Stop to Nant Peris.
Warner Bros were in the Never Never Land area a few weeks ago, so I'm guessing that this is the area most affected so a sensible low profile approach to other areas well away from Never Never Land would be ok, as was the case for the filming of Clash of the Titans.
Not worth upsetting First Hydro due to sensitive access issues, so please be respectful whilst filming is taking place.