Do these products need to be glued or nailed down to the slab?

It has to come up 28mm in total, to be level with the tiles in the adjoining hallway. The hybrid flooring will then go over both surfaces so they need ...

Would I be able to lay some particle board such as blue tongue first directly to the concrete floor then put a self leveller on top?

I am re-doing the floor coverings in my unit, upgrading to hybrid flooring. I’m not sure what product can be used after removing a section of carpet, ...