"Insulting or abusive words or behaviour is an offence under the Public Order Act."
Not any more it isn’t, danny. In 2014 the word ”insulting” was removed from Section 5 of the POA. However “abusive” words or behaviour still constitute an offence and the line between the two is often hard to draw:
http://reformsection5.org.uk/news/
Of course woofgang is quite correct, serving somebody who is drunk (or a person under age, a police officer in uniform or a working prostitute) is an offence. Most town centre pubs will almost be guilty of this in the course of a week.
However the police or local authority will not be interested in taking action in either of these circumstances. Your best bet is to appeal to Wethers’ good nature. I have had some “customer service” dealings with them and although they responded quite well I got the impression that they were somewhat going through the motions. Of course they should keep an orderly house but their idea of orderly and yours may differ !