As the lucky recipient of said parcel, I am happy to report the contents arrived in very good condition.
I think the foil, and a fairly snug sized bottle, worked very well to both keep the damp kitchen paper wrapped around the roots, and protect the stems within the bottle.
Plus, your new plants arrive with a free plastic cloche, foil for attaching to string to deter birds, and some damp paper for the compost heap ;D
I'm sending some plants out tomorrow, and I'll certainly be doing it this way...