Dusted crickets and mice make a good staple diet; other arthropods are good as well.

There is some controversy as to whether or not monitors need UVB. Frank Retes, probably the most successful monitor breeder in the world, says they don't and has had no problem breeding generation after generation without it.

What's more important is to have sufficient humidity while having a hot hot hotspot. Somewhere between 110-130 at the hottest spot is probably ideal. If you do use an aquarium with a screen top, make sure you cover most of the top with something to keep humidity in. Dehydration is death to monitors, so make sure you don't dry your monitor out. Having a burrowable substrate would help a lot in this regard, as humidity would be higher in the burrows. Not to mention, they will have the added security and comfort. Many people recommend plain old dirt. Cypress mulch and decomposed granite work well too.