Flexible changes
 

I have Ryanair flights at the start of Jan (worth quite a bit) I can no longer use because of the new UK isolation rules. Flexible changes only apply to end of Dec. Do you think Ryanair will extend this? The only solution I can think of to not lose all the money is to change this to a new flight/route for next summer, but with the change fees, it is almost not worth it... :(

I wasn't aware you could change route
I'm in the exact same boat
Trying to change to a date next year,any date,prompts a change fee that makes it cost more than dumping the existing and buying a new flight,so being at the loss of what was originally spent
There is no option to change route that I can see on my pnr

Unused tickets result in a return in taxes, but the taxes element isn't ever particularly big with Ryanair, and they charge an admin fee to make sure they don't have to refund it. :(

You can't change route without prompting a change fee.

Your best option is to await possible cancellation (which will allow you to rebook or apply for full refund) - or simply ditch the tickets if no sch. change or cancellation.

The best advice currently is never to buy FR tickets far in advance - for two reasons, (i) difficult to predict if conditions change and (ii) tickets are much more expensive if bought far out than 1-2 weeks before departure (I can say this from extensive experience with pricing of FR tickets). For flights in January (low low season) it would be an expensive mistake to have bought such tickets long time ago at presumably much higher fares than current.