I'd do it. Only that lens, eh!!!
Can you go and try a few shots with nobody there but with the same lighting conditions?
Not knowing how much ambient light there is (likely to be) any suggested settings would have to be
"all over the place". You'd be best trying those as starting settings. I wouldn't worry about the WB
UNLESS you are going to shoot in jpeg only. If there are coloured lights the Tungsten setting might
not help anyway. (I also dunno what light sources they have in discos these days. They may not be
tungsten.)
I dunno how you'd go at getting another lens. It seems to hire one would be putting you OOP ($).
Am.
P$: OOP means Out-Of-Pocket, but you must have guessed that