<<Not sure whether "should" makes it mandatory though....Bookworm?>>
Hey, we don't need Bookie for this one! should doesn't equal must. Even a simple ATCO can work that out.
It is all Class G airspace. That IAIP entry must be the result of someone with delusions of grandeur. Probably the same jobsworth who dreamt up the Mickey Mouse 'Land's End Transit Corridor which is a declaration of an AIAA to all intents and purposes. I'm surprised at the CAA printing it. Far better to be in direct RT contact with an appropriate agency should the worst happen.
Whatever, it's the South's best kept secret and a piece of cake to operate to and from.