What one "needs" and what one can afford are two different things. Obviously the UK "needs" an MPA with a robust ASW capability. It has none. Would an MSA be better than the current nothing.
Referencing another thread, perhaps the UK "needs" a rotory wing AAR capability. It has none.
Referencing yet another thread, perhaps the UK "needs" CATOBAR aircraft carriers. It has none.
Referencing yet another thread, perhaps the UK "needs" a nuclear deterent such as Trident. Yet there's plenty of talk, some of it quite convincing, that that capability is a luxury and should be scrapped.