I've just pulled up the old laminate flooring and underlay to discover that the concrete floor beneath is very uneven with a few blown sections in the top screed. The floor is a bit of a hotchpotch but I can't see any Dpm. In the ideal world I should probably replace the entire slab or better still expose the original floor tiles that i can see down the edge of the slab. However I'm looking for a cheap solution that will just do the job, so presumably some kind of paint on Dpm then levelling compound?