VinRouge is correct - Trident is not funded from the RN's budget. If anyone thinks that the money used for it would be deployed elsewhere in Defence, you're extremely optimistic. It will be used to pay the feckless to do nothing as well as all the other value-for-money areas that the Govt sink our cash into.
If we're not going to have a submarine based ballistic system (like every other nuclear power), then let's just not bother with nuclear weapons. It would be pointless (in view of its total lack of invulnerability) and probably more expensive to develop than simply continuing with a SM based system. We have almost 50 years experience of SSBN technology. On the other hand, we have never successfully developed a stand-off airborne nuclear capability (except Blue Steel and I don't really think success is usually a word associated with that programme).
But then it all comes down to the fact that we urgently need to have a national debate about the whole subject of defence and, by extension, our place in the World. At the moment we have a totally unbalanced pot-mess, which needs sorting. Pronto.