Extreme low-light and club photography is quite challenging.
My experience is minimal, but I usually got one or two keepers per roll.
One of my existing-light concert photos was once published in a book
not because it is particularly good, but because no other photos of that tour exist.
The crowd at most venues is less well-lit than the stage,
so movement blur at slow shutter speeds is a concern.
A small flash (when allowed) can be used effectively, but may ruin the "mood".
It might take several visits to start getting a good percentage of keepers.
Given all the variables involved I suggest you bracket your exposures.
Assuming you are not using a tripod a good starting point is wide open at your slowest hand-holdable speed.
Chris