[Closed] Painting mfp floor

Looking for a bit of advice before I go and make an expensive mistake. I've finally finished building my [s] nearly-winter [/s] summer house.

The floor is an mfp celotex sandwich type arrangement and I'm planning to paint it (screw fix no nonsense grey floor paint). Is there anything I need to do prep wise for painting the mfp beyond the usual filling of gaps and the like? It doesn't seem to be overly absorbent or the like so I'm guessing just roller straight on will be fine but I don't fancy seeing it all leech straight in and through to the insulation or blister the epoxy type stuff that holds it together.

Ta.