Honestly, I'd wait until he did it again and you get the absolute rage/upset bubbling out over you. Phone 111 and release the hysteria as you are only just post natal it is harassment at a very difficult time of your life. Repeat he's doing it to intimidate you. I don't suppose you are of a different ethnicity to him because I'd love it if you could call it a hate crime.
And then stand there outside and scream! And beep the horn on your car, and should you see twatty neighbour unleash the hounds of hell and explain he got the last 5 months for free because you were too weak to deal with his intimidation but you'll no longer stand for it.
Going to the Daily Mail with the threads is a pretty good idea.