Summerhouse interior walls

Me again!

Bit of a weird one but I want to wallpaper the inside of my 'log cabin'. I am going to turn it into a traditional looking pub.

It's one of those summer houses made from 28mm T&G.

Obviously I can't wallpaper directly onto the T&G so was going to put Plasterboard onto the wall first.

Should I put some sort of moisture control sheet between the T&G and the plasterboard to prevent it getting damp? If so what type of sheet?

I don't want to insulate the walls at this stage, the roof and ceiling are well insulated.

Cheers