I have kept and bred monitors for 20 years. They do not need uv lighting. It wont hurt them if you install UV, but it is not needed.
Dragon lizards definately need UV for them to produce vitD3, which in turn allows them to absorb calcium. Snakes and monitors from my understanding, DO NOt produce their own vitD3 from UV lighting. They in fact get their vitD3 from the preys livers when devoured.
It still amazes me when I hear of people giving 8, 10, 12 hours of UV to pythons. Dont you realise that pythons are nocturnal. Not much UV from the moon. Some pythons may bask in the early morning sun ever so often in Winter, but its never more then a few hours and its only to warm up after a cold night.