Insulation under floor

[vintagegt1]

We’ve bought an old Victorian terrace and it has an undercroft/cellar type space with a gap ranging from 5 foot or so to about 3 foot at the front of the house.
We’d like to utilise the bare floorboards as our downstairs floor but would obviously need to insulate underneath as it’ll be freezing in the winter.
Couple of questions- can I use block wool/rockwool type insulation in the gaps (see photo) without worry of any damp occurring anywhere and what’s the best method to secure it in place so it doesn’t just drop out?

Picture attached for reference which shows the entrance hatch. Any advice much appreciated.

 

[vintagegt1]

Sorry, can’t add the picture as it’s too big apparently

 

[nero44]

If I understand it correctly, then the answer to your questions is yes. And it is really important to secure the rockwool, to allow for sufficient ventilation underneath on airbrick level. I am doing something similar in my victorian terrace and am using some netting and a cheap electric stapler. Inspired by this video. This is quite an onerous task, but certainly worthwhile, while you got access.

 

[vintagegt1]

That’s fantastic, really helpful. Thank you.