From what i have gathered so far, you are permitted to import rootbark pieces, but not the rootbark powder- as this is considered as a DMT part preperation. As long as you are ordering these pieces for legal purposes as in external use only, not for re-sale, for use as a dye, skin treatment, etc, then you should be able to order. Best check this with customs and excise first.
-There are sites that send direct from Brazil, and they are now sending the rootbark pieces only, because of the powdered shipments being seized. mh-UK also has rootbark pieces for sale, as already stated.
-I hope this helps.