So I know they are both classics. Back then I was not into first person dungeon crawls. Should I play 1 then 2 or just skip over 1 and go straight to the 2nd one?
1 can be played by itself. In theory, it goes between U6 and U7 but in practice it stands on its own pretty well as it doesn't really tie into the rest of the series that heavily.
2 should be played between parts 1 and 2 of U7 as it ties into the plot of those games a bit more.
Also, UU1 is widely regarded as being a better game than UU2.