Last August I took my IR stuff down to Gatwick (rather than risking posting it) as it had to be in within 6 days as the exams were about to expire. (Talk about cutting it fine
)
I got there 11.30hrs and the foyer was empty: not a soul waiting.
The nice lady checked through all the stuff for completeness, signatures etc, and asked me if I'd like to wait as they could do it there and then, but it would include a wait over their lunch break.
As it happened I couldn't wait as I had stuff planned so left it with them: Took 10 days to return it.