Get the full mod from the official GOG section on the Fallout London site or Nexus mirror. Look for: Fallout_London_v102_iv233r7_GOG_Installer.exe
[Archive] bInvalidateOlderFiles=1 sResourceDataDirsFinal= [General] sLanguage=en fallout london v102iv233r7 gog install
After installation, you may need to configure some settings to optimize your experience: Get the full mod from the official GOG