An NVQ was a type of qualification.
Barclay studied in a two-week NVQ course in the local garage, but he didn't finish the course. Despite this, this contributed to his knowledge of engines and mechanics, leading the Doctor to reccomend him to UNIT, for his good skill with engines, after the San Helios crisis was over. (TV: Planet of the Dead)
Ryan Sinclair was studying an NVQ in order to become a mechanic. His studies enabled him to fix a solar-powered boat on Desolation. As part of his NVQ, he also learnt facts about acetylene. (TV: The Ghost Monument)