How continuing British carrier construction changes the early war

Could Britain still improve its fleet after 1939, and what would extra carriers change?

Yes; reversing the carrier pause could have altered several early operations while natural bottlenecks limited the impact on escort construction.

Extra carriers create second- and third-order effects rather than merely adding hulls. They could enlarge the Taranto strike, provide air scouting and attack power to Home Fleet groups, and change the detection and coordination problem at Denmark Strait. The same ships could support anti-submarine warfare and commerce protection, roles the Royal Navy had already identified before the pause. Existing turbine bottlenecks meant continued carrier work might delay some escorts only marginally rather than displacing the whole program.