They like to visit before baby is here to introduce themselves and give you babies red book, ask if you need any extra support with anything etc, that's it really. I know the HV service is now newborn to 18 years old and the service is stretched thin but they are a good service, they were an absolute God send when it came to my sons cmpa as they helped with a feeding specialist and the dietician referral when we was constantly fobbed off by the GP x
I didn't have one with my first last year it was literally a phone call from the health visiting team and then I had a health visitor home visit once he was born.
We're moving house a week before baby is due so our HV isn't bothering with an appointment. I think it's a nice thing as means you get to meet before baby is here but no hassle if it doesn't go ahead