Locker wait list is a pure luck thing not time, lots of us have been complaining and movement is happening as the main problem was crew commuting from Europe etc and storing their uniform in said lockers for weeks at a time.
You can opt to share a locker etc and now the ops team are requiring a copy of v5 and insurance to prove bike use so it is improving.
As for theft.... it was the heathrow airport police who gave me that advice!