Is there a Discord or Nexus page to get official support? Thanks.

Why would there be that when GOG hosts it?
Technically THIS should be the support forum, but they've bunkered up on their discord.

Theres an invite to it on their site: https://fallout4london.com/

From what I understand, there is ongoing work to address the bugs. It's unclear to me how many of them are fixable, but I'd expect they'd at least be able to fix the showstopper bugs that prevent people from actually playing past the tube train, even if the game does still crash ever hour or so.