Please feel free to educate me! I am happy to learn. I can only respond to your question by another question: if not NATS's website, if not the CAA's website (who surely oversee NATS don't they?), and not the AIP's website (AIP stands for Aeronautical Information Publications - does it not? Is this not an aeronautical publication? [which the common person can understand without requiring further discussion with a lawyer!]) - where DO you find the guide? And more importantly, where do you find ALL guides for flying in these regions in one single place, reliably updated every time a change is made?
The Farborough LARS is funded by NATS En-Route Ltd and TAG Farnborough Airport Ltd. If they decide to produce a guide it is up to them to decide where to publish it. They chose to put it on the Fly-on-Track website, which has a wide audience.
The guide is not found in the AIP, because it does not conform to the
ICAO format and CAP 1504.
Why do you expect to find guides to fly through other bits of UK airspace?
I am not surprised you are disappointed with the service you received from the CAA, but the FAA website today reads: "We are currently processing permanent Airmen Certificates for temporary certificates that were issued approximately November 15, 2016." Yes, I know you can fly on the temporary certificate. That would solve a lot of problem if adopted by the CAA.