Mills are a very northern thing.., towns such as Bradford and the surrounding areas are full of them. You will have locations in the South though, they are country-wide.
They make for a great adventure, are borderline legal and make readable posts on here! Whereabouts are you, I might be able to find a few..
Near Salisbury Originally and now South West London, got some lovely old WW2 structures nearby and old airfields - I lost all my old credentials to the Urbex Forums and now theyve understandably gotten tight with sharing the info so any tips you got would be brilliant! (Borderline legal😂😂😂 love it, and they really do make for good content)