Could the RN afford a escort fleet and trident subs if 3 CVA were obtained?
Most AH.con members fail to realize that the Trident programme was and still is the biggest money grabber in the UK defence budget.
Not without a stronger British economy which will be required ITTL anyway. IOTL the Knott Defence Review of 1981 was because the UK couldn't afford to maintain 3 helicopter carriers, 60 destroyers & frigates and replace Polaris.
However, the CVA.01 class would be built in the 1970s and Trident wasn't built until the 1980s, which will help. They'll probably go for two ships in commission and the third in refit/reserve which what they did with the Invincible class IOTL after Invincible herself was reprieved in the wake of the Falklands War.
However, two CVA.01s even with their reduced air group require about twice the personnel afloat and ashore as 2 Invincibles. OTOH some of the RAF's Phantom and Buccaneer squadrons took the place of FAA fighter and strike squadrons. ITTL the 4 extra FAA Phantom and Buccaneer squadrons in the 1980s would be offset by a corresponding reduction in the number of RAF Phantom and Buccaneer squadrons.
There won't be an Invincible class if CVA.01 isn't built which will help too. Although they are roughly in the gap between the CVA.01 class and the Trident submarines they money could be spent on more frigates and destroyers. But my preferred option would be 2 or 3 new commando carriers to replace Albion and Bulwark.