Whenever I got to gigs at Birmingham Academy, they start around 7/half 7 & I have to make sure I catch the train back, the last train usually being at 11:20pm & I've never missed it. Gigs starting at half 7 are probably likely to finish no later than half 10/11. The annoying thing about gigs I find is all the waiting around; half an hour to an hour for the support act to come on then half an hour for the actual band. It's worth it though!