when i ran an event on york campus we had all kinds of nasties from the health and saftey people - nothing on celings whatsoever, no attaching anything to the walls meaning we had to get extra truss in to hang everything from..
anyway, for a strict venue you have to have insurance (we were told any people coming in from outside the uni would need £5m worth!!!) and everything has to be fire checked by the fire department. I was given the impression that spraying isn't really good enough, but if you get a certificate for it, no one could say anything against it.
fortunatly most venues are a little more down to earth than the uni people, so the most important thing you can do is to be sensible - don't put anything risky anywhere *near* any lights or within reach of punters if at all possible.
H&S people seem to be under the impression that everyone who attends a party is an accident waiting to happen, but then if it goes wrong they'll be the ones knowing they saved lives..