Yeah you only need UV reactive dye/coolant OR UV reactive tubing. You don't need both.
UV is ultra violet light, it's actually invisible to the human eye. however, when you buy UV lights, some of the light they emit is just below the ultra violet spectrum and is a visible violet. That's why they're all purple.
For PC, you can get either UV LED or UV cold cathode. There are a lot of reports that say the LEDs basically destroy the UV reactive properties of the dye/tubing and tend to fade things. UV cold cathode are much better in this regard, and your UV reactive components will stay UV reactive for much longer.
However, cold cathodes require a little inverter - it'll come with the cathode of course, but it just means you'll have to fit a little box somewhere in the case. Not a huge issue.