"Is there more than one type of UV inks? "
NO, there are
- flexible ink for flexible media - AKA soft ink and
- hard ink for non-flexible media, like glass and metal.
"what's the best type of UV ink to use on a regular Epson printer?"
NONE as long as you don't have a UV-LED to cure it. UV ink never dries - well, it would if you put it in the sun (UV ray). But till then it won't.
If you installed UV-LEDs - it depends on that you print on.
"without any modification, is this true?"
NO, an L805 has no UV-LED build in.
I hope that helps.