score:1
Short Answer: No
Long Answer: no, but of course insurance is a good thing to have, it is just not a requirement for the National Visa D application for Italy from the UK. If a document is not listed on the VFS checklist it is not a requirement for an application.
Source: 3 separate VFS agents
I rarely see follow-ups of those asking visa questions after they have gone through the process.
I have just finished the visa process and can confirm at no point was I asked for my health insurance or any supporting documentation for health insurance.