Yes, councils normally inspect for potholes and can then claim that a bad hole developed between inspections, but had not been reported. The thing is, in this case it sounds like the people who removed the cats eyes caused the potholes, and then did nothing to rectify the damage. To me, that smacks of negligence! How can you cause the damage and then say that you didn't know about it?
Just managing expectations here. A claim against a council for public infrastructure matter is vastly different from a straight forward claim against the person behind a vehicle that crashed into a cycle. Potholes are ubiquitous across the country and requires extensive funding to cover the ravages of the weather. And funding is limited. So such claims are generally difficult.
As
@C R pointed out, there must be a prior complaint and evidence that it was not addressed given sufficient time. And it cannot be a general complaint that a particular road is not maintained. Evidence that's others have fallen victim to the same road is good evidence. A public appeal on local facebook or community rag can be extremely helpful.
So in a nutshell it is not the usual cycles related injuries that the usual cycle specialist lawyers can handle. In this case, solicitors that have taken on council and public authorities on infrastructure maintenance negligence would be a better bet. These are guys that handle claims on fractured ankles due to damaged but unrepaired pavement, trees that fall on a person due to noticeable root damage, failing to provide adequate road signs etc.
Just ask the solicitors picked, on the probability of success, particular council's history of settling etc. And most importantly total cost in legal fees if not successful. Also ask them to include the council's legal fees that might be imposed which can be a possibility.
Hope this helps.