Have a look at the ndb procedure for 33 in the AIP.It has a table of "recommended" ranges /altitudes, your reference is on the noise page!!If you have never been to BHX when the ILS is working on 33,(it must be over a year by now)you follow what it says on your ndb chart.If the CAA dont put it on their approach charts what hope does somebody who is probably an infrequent visitor have?These restrictions are usually buried on the same page as advice on running apu's on stand.