Have no idea myself about
your system either, fella - but our GASOs lay down minimum requirements for accomodation that we tend to adhere to when not on deployed ops (ie transiting) - and therefore not having an additional risk like disturbed crew rest signed off on.
It may well just be that Akrotiri were doing the standard stacker's trick - "You can't have those rooms 'cos somebody else might need them" - or they may well have been already booked for somebody else. Also, we would usually know whether we are planned to be on- or off-base before we leave home base - the classic is when the APCs are on, and there is hardly any on-base accomodation available!
Oi, Boyassasin - be nice to tonkaboy now! They're not as battle-hardened as we are nowadays and might not be able to take your fierce banter.....