I wouldn't worry too much, I'm sure it'll be possible to find out on the day from Pr's etc.
The tickets tend to be pretty generic so unless it seems they have been specifically printed for the Faithless gig then I'd just wait and see.
I would expect the club to open at 11 with dj's on warm up then Faithless later on.
I notice that on ticketmaster the opening time is the same as your ticket 23.59, bit of a strange time.
I'm sure that the event will be heavily promoted closer to the date.