There is some very worthwhile advice here.
I would like to reiterate that the police will be reluctant to listen, reluctant to write anything much down, and say they can’t do help much. Make sure to write down the name of the police person you speak to and it must be a police person , not the desk person who is often a volunteer, not a copper. And you must leave with an ‘incident number’. As I said, if you jump up and down politely and are upset enough, they may offer to contact the harasser.
Also, remember the threat of a complaint that they wouldn’t help you often works.