I bought the GOG version to have fewer issues than downgrading my Steam copy. Then I did all the steps as put forth by the FOLON team, it kept crashing at the train ride, I added F4SE and Buffout4 it was much better then. I stepped away with other distractions for a week or two and when I returned my most recent saves were not available in game but I could locate them on my drive... I will return when Team FOLUN gets this on all four wheels, yes it's a free mod, yes i enjoyed PLAYING it, but I didn't enjoy retweaking settings, or wondering will it launch without locking up.

It won´t get "easier" as a total conversion has to be handled a bit different then a simple tiny single mod.

You might have missed that there was a patch some days ago that has to be installed manually. Your gog downloader should have downloaded that automatically. You then have to start fallout london on it´s icon and on the next window don´t start fallout london but instead click on the update button. Might take some time.

As i said, it won´t really get easier in any way.

There is also another step that has to be done manually after updating, and that is to go into your Fallout 4 GOTY\Data folder, and run "LondonWorldSpace - ClearUp.bat" to remove an old plugin that was causing stability issues.