Which loft walling?

[Lee27]

Hi,

Ive just finsished the floor on my loft,and want to seal it in.Which material should i use to do loft walls? The loft is being used for storage and to display a collection of mine-but it is not a habitable room and i will go uo there once maybe twice a week.Also,im a little concerned about condensation when ive completed the work as im putting a carpet down on the floor-how can i avoid this or any damp problems?

Thanks

Lee