19x (~10m2) Fibreboard 5mm underlay (Wokingham RG41)

Same as the stuff linked below, there's 19 whole sheets plus a handful of various sized offcuts which take it to the pack size.

It is not *quite* flat, there's a slight bend of a few mm by each end, but is otherwise clean and dry. How much that matters depends on what you do with it I suppose, personally I wouldn't use it for the intended purpose but I'm no expert. Just somebody who wouldn't want to do it twice and knows what the "hollow floor" sensation is like.

https://www.wickes.co.uk/Wickes-Wood-Fibre-Laminate+Wood-Flooring-Underlay-...

If anyone does want it, big priority to swift pickups.