I think for organised sport i.e. professional and semi professional they will start postponing games or playing them behind closed doors, especially if there is a sharp rise in the number of infected people in the UK (like happened over the last week in Italy).
It would it take 1 person at a match to potentially infect 10s of people, more if you factor in public transport to and from the game etc.
At grass roots it would be harder to implement, so I wonder whether leagues would just either have to postpone all games indefinitely, or just bin the remainder of the season.