The only light a gargoyle needs is for daylight cycling. The only time they would need a heat source is if your room temps are in the low 60's or colder; in that case a 40w above the screen top would work fine. Gargoyles live very well with temps between 62-82. They can tolerate temps between 45-60 for short periods of time only and temps above 82 for even shorter periods of time.
Lights are only necessary for plants and cycles as already mentioned. I do use simple flouresent strip lights on my garg enclosures on timers as I like some lighting and some have live plants. But in a well lit room with fake plants lighting isn't essential.