laminate flooring underlay

[vik2001]

Im going to put down underlay in my lounge. half of it is concrete the other part of the lounge is wooden floorboards. whats they best type of underlay to use where its half wood and concrete?
is there a underlay that can be used across the 2 platforms?

 

[foxhole]

Laminate underlay is suitable for both, a plastic sheet over the concrete before underlay will prevent moisture movement into the laminate.
If the floor is not level then over-boarding first will be needed.