In popular movies, ordinary people seem to be able to just turn up and join a police academy. Is this still the case or do you have to go to college to be a cop?

These days most police forces require you to hold at least an associates’ degree, but this will vary police force to police force. You should check the entry requirements of the force you wish to join. There are some who do apply to become police officers with just a high school diploma, but as with most career paths, holding a further education qualification may hold you in better stead.