If you want to play that whopping Fallout London mod you'll need to downgrade Fallout 4's "next gen" version
We haven't written nearly enough about Fallout London, a gargantuan Fallout 4 total conversion that takes place in a whole new map based on England's capital city - the Big Smoke and/or Great Wen, whose real-life incarnation probably harbours at least one nuke at any given moment, though I haven't asked the King about that lately. Best not speculate.
Anyway, Fallout London is a huge effort from modders Team Folon that was recently sabotaged when Bethesda treated Fallout 4 to a next gen update to capitalise on the Amazon TV show's popularity, rendering several mods incompatible and breaking a lot of stuff. Team Folon have now fiddled with the workings and sent a Fallout London build to GOG for QA testing, which suggests that release is imminent. The catch, however, is that you will need to downgrade your copy of Fallout 4 to play the mod, because even with Team Folon's last-minute adjustments, Fallout 4 next gen and Fallout London simply don't get on.