What happens if there are not enough people in the attendance list?
The Game Organiser will always try to get the game going because usually they pay in advance the pitch hire cost (which is not refundable). As they are aware of the venue situation, pitch size, if are people hanging out in the venue they will be able to make a decisions without compromising the quality of the game.
For example if there is a 5 a side game and are missing 3 players, usually the game will be cancelled at least 2 hours before kick off time. If you signed up in a 9 a side game even if there are 15-16 people in the list most likely the game will go ahead.