Bose-x
Airport operators only promulgate changes in the UK AIP... Jepps, Aerad etc. all pick up there changes from there....so, in theory, the AIP should be up to date.
The Rule 5 issue relates to overflying the congested area...I don't know what the procedure profile is, but assuming the Airport is somewhere near the City during the approach, you could find yourself in breach.
The caveat is you can break all the Rule 5 requirements when taking off or landing 'in accordance with normal aviation practice'. These days, I'm sure a good lawyer would argue that flying an out-of-date, unpublished procedure is not 'normal aviation practice'.
The CAA did issue a consultation document last year about the use of Instrument Approach Procedures at airfields with FISO, but I understand that it died a death....the can of worms it opens is bigger than the one we've already got with people making up there own procedures on the back of the proverbial fag packet!