I remember COIN was one of the questions in the B-exam 45 years ago. Cheap, cheerful, and plentiful versus expensive, sexy, and few. The OV was around then IIRC and the Vietnam war was ramping up.
I guess the major limitations then were slow transit speeds, lower bomb loads, and greater exposure to enemy fire. The Sky Raider over came some of these limitations.
We no longer have a trip-wire strategy and possibly only need multi-capable invervention forces to hold the line for a year or so. Accepting there is no cash in the kitty, we would keep things like a COIN capability on the shopping list, along with mine- protected vehicles etc, ready to ramp up production and bring in to service in a couple of years.
Rather than invest in amphibious warfare ships that will probably be in the wrong place at the right time we could concentrate on STUFT instead as there will always be cruise ships at Southampton capable of carrying 3-4,000 troops (assuming we have that many).
We could apply a similar logic to helicopter carriers and accept that a single fixed-wing carrier could not apply airpower without shore based support.
The surface fleet could be optimised for close in defence against coastal SSK and light attack craft and have a limited AAW capability for the protection of STUFT.
Only long-lead items like the RN Escort vessels, RAF intervention capability and aviation R&D would be funded. The Army has probably written off its heavy armour already and MLRS is also a gold-plated asset. Heavy artillery too is probably over-kill for the moment so it would be better to maintain multi-role production capability rather than buying expensive equipement.