I agree with wilebill. Urgoz and UW especially (and the Deep, honestly) are not areas that you just fall into in HM and "figure out as you go along." All of these areas punish you for mistakes by kicking you out. Read up on them, watch some YouTube videos, learn the basic tricks, then give them some NM test runs with heroes. Once you get the lay of the land and understand what the enemies do and how the quests work (in the case of UW and FoW), you'll be better prepared to PUG. I would honestly suggest going for NM first. Once you've gotten all the way through to the end (which can often be the trickiest part) and completed it, only then, I think, will you be ready to tackle it in HM.
As for the scarcity of PUGs, as with anything, they're most popular on/around Zaishen Bounty days. I'm not too sure about UW/FoW groups, since all I ever see around ToA are speed clears. You might want to hit up the
Grouping Section here on Guru. If you're up front about your level of experience and what you struggle with, people will be better able to prepare and help you and not just rage if you screw up in a random pick-up.