Harvest time window! But can I use heat uvbulbs as apossed to a heater to keep room at optimal temps? I know heater will suck out all moister and humidity?

Sucking out moisture and humidity will not be a problem at all, in fact it will help prevent moulds or fungus from developing in your flowers. Cannabis is not a rain forest plant and does not really need artificially boosted levels of relative humidity, apart from cuttings/clones. A dry atmosphere will even enhance trichome production to guard against the over heating of the ovule located at the base of the pistils. If all your pistils have already browned off, peak THC production has already passed and you should be harvesting soon, so even if you are worried about RH, your plant will hardly be in a dry atmosphere for very long anyhow. Remember to dry your flowers in darkness, drying them with direct light on them will cause any remaining THC to degrade even further. Hope this helps,.... Organoman.