If your room temps DON'T jump around much, then you can get by with just a rheostat (a light dimmer). Find the sweet spot on the dimmer switch and leave it. BUT that will ONLY work best in a room that has consistantly steady temps. Otherwise, you're dinking w/the dimmer as often as the off/on of the heat lamp.

Heat lamps, or CHEs WILL work, but they MUST be on thermostats to keep them from getting TOO hot. Your UTH should be on one too, just to be safe. So for that, yes, you'll need the herpstat with two separate controllers.