This came up in the Yated chinuch roundtable within the last few months. The general concensus was not to get too hung up about it, it’s normal, not unhealthy. Maybe things are a bit different in the UK, especially since in the US, some frum kids actually go to ball games; in the UK I’m sure no one does.
I wouldn’t try to put a complete halt to it but would try to not let it become an obsession. My son loves reading about sports but we are limiting the number of sports books he can take out at a time, and no biographies of individuals, to discourage hero worship.
My guess is your son will outgrow it if handled well.