I *hate* to point this out
But roughly 20% of the UK electricity supply is nuclear. That's *very* roughly 14Gw of power.
They are all getting on a bit (IIRC Sizewell B is about the youngest and that dates from the late 80s?). Something has to be done about that hole *now*. Ideally something which does not increase the national carbon footprint.
Windmills still need a backup supply. Coal (UK reserves about 200 years) but carbon emissions. The UK could do a *lot* more with Methane production and the Scottish tests of 2Gw of Tidal and wave power systems should *finally* see some clear winners worth investing in. The UK has a *huge*, nearly *unique* (in Europe) asset of its coastline. one of the UK Islands (Channel, Isle of Wight) has the largest tidal range in the *world*. Predictable, massive power pulses which will run till the Moon's orbit decays to Roche's limit (that will take a while).
As for Trident. The ICBM in a sub gives the absolute *best* in stealth (70% of the Earth's surface to hide in) and penetration. Nearly 6 decades and probably a teradollar (1x10^12) by the US have *failed* to find an effective way to shoot down an incoming warhead. Putting cruises on big nuke boats retains the stealth but (depending on the opponent) may fail to penetrate their airspace (the UK baseline target was always Moscow. It was felt given its size if it couldn't nuke the Kremin it wasn't worth having).
Their are *very* few ICBM suppliers in the world. The UK has *always* bought American.
It's not clear what the UK can still do on its own. Some out of the box thinking might pay dividends. Shift the Tridents to fixed (sea based or land based) sites. Strip the warheads (I think they are UK mfg) slap them on some kind of EM launcher. The UK has a pretty solid track record in high power pulse systems. A true nuclear cannon.