Would it damage my helleborus and peony if I was to cut back the folage now .
If the foliage is in good condition, then yes, the plant needs its leaves to feed itself. You could judiciously remove any dead or dying leaves, but do not completely defoliate the plants at this time of year.
I'd certainly leave the hellebores for another couple of months at least.
I do hellebores around the turn of the year. I pick up the paeony leaves when they come loose
i agree i always leave the leaves on so the plant can get a feed from the leaves