When we did ours I took a photocopy of everything just in case.
The Immigration Officer looked through our papers, took some away (to copy I think) then after the interview just told us to come back.
He didn't ask us for any copies.
Personally Tone it's better to take a copy anyway.......it's just impossible to predict what's needed as copy and what's not.
Sorry, best I can do.
Others may have a different experience