What I have been told and I still can't quite believe it's correct is that the original flight although it doesn,t actually exist any longer is not cancelled and that my flight has been rescheduled even though my flight number has been changed?
If it's a different flight number it's a cancellation
I will be entitled to change to another flight or refunds as the the change is over 5 hours but not until I am officially informed of the change?
That only applies for schedule changes. Your situation is a cancellation
Also if the flight moves again to less than a 5 hour change before they let me know I will not be entitled to this?
If the flight number is different it's still a cancellation
Unfortunately, Ryanair are unlikely to send you an email about the above until about 90 days before departure. Until you get the email the agents won't do anything.
Once you get the email, you can rebook on same route, reroute or refund or accept their proposed itinerary