OP, I had a very bad experience with a HV when I weaned my premature twins early (on the advice of the neonatal consultant we were still seeing) and she told me I would have "damaged my children's digestive systems beyond repair".
I then had a telephone call about 5 months later asking me if my DD was ready for her heart surgery the following day. Back story was that my DD had been born with a minor heart condition but before we left the neonatal unit, we had been told it had corrected itself, but would be monitored. You can imagine my shock and worry when I thought she'd have to have a heart operation. I said I didn't know anything about it, went through the whole scenario, in tears at this point. Turned out there had been another set of twins born at a similar gestation to mine, and the girl had the same name as my daughter. The HV said "oops, looks like I've got the wrong baby - I'll have to get the file out".
Needless to say I put in a formal complaint. She was telephoning parents about a planned heart operation without even having the baby's details in front of her. She said she had a list of numbers to ring.
Long story short in that HVs are not trained on premature babies, particularly if they are born v early. If you have any worries or concerns at all my advice would be (and I know I'm not objective and there may be some HVs that are good, I've just never come across one) to bypass the HV completely and either go to your GP or telephone the unit.
My premature twins were seen by the consultant who'd treated them on the ward until they were 2.