No lights - especially UV. If it helps, my 24 year old has never had any sort of light and he seems to be doing well. Some reptiles are dependent on UV to produce vitamin D. This helps them metabolise calcium, so without UV these reptiles will develop skeletal deformities. However with Corns, as has been said above, they're active at times of low or no sunlight and have never evolved this dependency. General pet stores can trot out the "all reptiles need UV" line as a default if you don't speak to the right people - it covers their behinds for some species and allows them to sell extra equipment and consumables.
As far as a day/night cycle goes, as long as the room they're in gets some kind of natural light through windows or skylights, then they'll be absolutely fine.
I'd advise getting the max floor temp to 85. 90 is their safe maximum. If it gets to 90 or above for any length of time and they can't get into a cooler zone of the correct temp (low-mid 70s), then you risk neurological damage to the snake.
Corns like it surprisingly cool. When you think about it, human core body temp is around 96 - over their safe maximum. Whilst the surface of our skin is cooler than that, if you put your hand on a heat mat which is set to 85, it should barely feel warm to you. It took me years to feel comfortable with how cool Corns need it.
I'd echo advice about getting a good thermometer. One of my nephews got one of those plastic dial types with his starter kit and it didn't even move when the heat mat was accidentally switched off at the mains. They're very inaccurate. If one of these (or a cardboard strip type) says 90, then the actual temp could be anywhere up to 110 and beyond.