No, you can't really say that most Colubrids are nocturnal. Many are (such as Trans-Pecos Rat Snakes), and many are during the hottest weather but diurnal during cooler weather (Eastern Kingsnakes). Many are purely diurnal (such as Coachwhips). Some are more crepuscular during the hot weather, but are still diurnal. Some can be found moving around just whenever the mood strikes them.
As far as UV lights, that may be beneficial to those species that often bask in the sunlight in the wild. I don't know that UV is necessary, but a basking light would be for those species. Those that are fossorial in nature probably don't need a basking light. The key is that if you use a basking light, they also need the option of a cool hiding place away from the heat and light.
Your best bet is to decide which species you are interested in, then research that species to find out what it's natural habitat and habits are. Then you can build it's environment to suit it's needs. There is plenty of information on this site as well as many others on the web. Kingsnake.com has a good search function. Almost any topic you can think of regarding a a particular species has been discussed at one time or another.