Unfortunately you're not on solid ground with respect to Ryanair's T&Cs, there being very few options open to you. But don't give up, give them a fight.

Raise a formal complaint with Ryanair, perhaps argue their unwillingness to assist may constitute a breach of the Consumer Rights Act 2015 because they have arbitrarily changed the flight times by almost 5 hours (perhaps suggest a retiming intentionally chosen by the airline to prevent you relying on Ryanair CoC) and that the term allowing them to unilaterally change the timing of the flight by 4 hours 55 minutes is an unfair and iniquitous term given that you would not have that option without paying a significant financial penalty. Advise them that their schedule change means the service as is now scheduled is no longer fit for purpose because their time change means you cannot possibly use the service purchased as originally intended.

They may or may not move, I suspect not. Once you have exhausted the complaint (this must be in writing - email is fine) ask them to provide a "deadlock letter" and make a formal complaint via ADR: How to complain about a Ryanair flight | Cancellation | AviationADR