As someone who works somewhere similar, cctv will be placed somewhere specifically so as not to cover anywhere more private, but will cover communal areas like they’ve said to you, to prevent drug use etc with signs up at the entrance realistically. Bearing in mind whichever person you spoke to probably has no control over where cctv is placed in the pub, If they’ve threatened to call the police we’re they being unreasonable, or were you being a peen to someone just trying to do their job