Some good points here about many weapons projects crossing party boundaries and of course exceeding the life of parliaments . Thing is can we really justify even what we have got in terms of military unless it is combined with other forces.
Realistically that means the Americans where we are just along for the ride or Europe where we are one of the larger powers and probably have a fair amount of influence -France being of similar size and it seems we cooperate quite a bit with the French even if some people do still see them as potential foes.
I have always presumed that as our nukes are American we cannot actually sue them on our own. so as well as what equipment should we have is a question of what alliances and that would also extend beyond any one aprliament.
As for Jeremy C I would trust him more with a nuke that Mad May who seems to have completely lost her mind since becoming PM and looks like she would nuke someone for criticising her hair do