CAP 413 used to include the ICAO standard phraseology, expanded where ICAO was silent or a bit vague, together with national variations. Specific requirements for particular units, airspace or airports, where they existed, were published in NOTAMs or the AIP. I've not been involved in the book for a long time but if the same principles are being applied you won't find anything about it in CAP 413, especially if it was only a trial (despite the fact that some trials can go on almost indefinitely). FWIW, I recall that there was an entry in the book about initial calls to an ATC but it wasn't very detailed because of the multitude of variations that exist.