If you don't mind, a type 14 upgrade option (twelve scraped in the 70s/80's, built/commissioned in 55-59 so later than the Daring class)
Using gas turbines (Exmouth was the RN test bed), 2x40mm
(now 1 + rim72
), homing torpedo's, flight deck, 2 RIBs.
This has a very light weapon/sensor load but if all you are really doing is policing why not ? (will Argentina be willing to sink 3 ships and have a real war ? that or go for a high/low mix with another high end ship [such as your guardian or a new build type 21/22/42 ?] or on shore aircraft/helicopters ?)
And it is cheap so should appeal to the Treasury.
(my only reservation is if I should give a limited AA capability, thinking about fitting a phalanx or a light weight missile but weight would mean I would probably have to swap it for the 40mms or at least one of them)
to add AA I went with (rim 72 Chaparral) as it would not need a director and thus may not blow the weight budget. (I know its not very good would Sea Cat or anything else be better ?)