Even if we need JSF, for FCAC, we don't necessarily NEED a carrier. Most of the allies who participate in coalition ops don't bring carriers to the party, and are able to make a worthwhile contribution. Nor are carriers necessary for autonomous ops.
Carriers are an exceptionally expensive way of delivering relatively modest effect, and they are vulnerable, slow to deploy, and require massive and expensive support.
In the real world - the world in which we cannot afford every club for the golf bag - I'd rather rely on the Spams in the distant eventuality that we need carrier air, and instead make sure we have our own autonomous SIGINT, our own, 'bought and paid for' tankers, lots of SH, a proper Canberra replacement, SEAD capability, low collateral damage weapons, sufficient AD aircraft and lots of deployable FJs. As well as proper kit for our troops on the ground, radios that work, appropriate vehicles, etc.
We need every Typhoon we've ordered, and (in any case) very little (if any) money would be saved by cancelling Tranche 3, since most of the cash is spent, and penalty payments would take care of most of the rest. And I suspect that if we were going to flush MRA4 to save money, we should have done it a decade ago.
I'd agree with you that the Reds, and Scampton are indefensible, and that they should probably go, along with Victory and all that historic Portsmouth stuff, at least one of the naval bases, Dartmouth, the Household division, the King's Troop, RHA.
And the RN is responsible for some of the budgetary pressure. The Admirals were told Trident replacement or carriers, and they're pushing for both, when neither are strictly necessary. We could and should have a cheaper deterrent - even if it remains submarine launched. The Moscow criteria is no longer valid, nuclear SLCMs would be more than adequate.
As to the money wasted on Nimwacs - that was spent decades ago - it's like blaming the CVA01 cancellation fees, or the last refit to HMS Rodney.
Whereas there is a great deal of real saving (money that hasn't already been pissed away) to be had if we deep six the CVF and JCA now.