Yeah it would be pretty cool to meet up for lunch or dinner the day before the game.
Euhrm, tailgate...
1. London doesn't have a NFL Europe team anymore (for 7 years or so).
2. Tailgate at a soccer match? They are more likely to kill each other (which they sometimes do).
3. No NFL Europe team has tailgates.
4. October + England = wet, cold and windy
5. Closest thing to a tailgate party we have in Europe is the Frankfurt Galaxy where they have Apfelcider parties before the game starts.