Nuclear Subs not necessary? why pay 100 billion

We can still keep a nuclear deterrent - land based firing solutions exist. Mounted on trucks or on MOD property. We have at most 40 missiles. USA has about 1600 when i last looked twenty years ago. We cannot fire ours unless we get the USA's permission so It's unnecessary? It's a tax for the USA.

When we proved we had nuclear capability in the fifties, instead of building an independent nuclear arsenal, the UK leased polaris missiles from the USA. Ever since the UK has been basically borrowing missiles? If we were to ever fire one they'd be controlled by US technology.