The other problem with TLAM is we don't have any warheads to go on them. The UK has always designed and maintained it's own.
Trident may share it's technology and "blunt end" with it's US brethren, but the bit at the pointy end is designed and built at that place in Berkshire.
We can't convert and fit the tactical warheads either. They were decommissioned several years ago after the RAF had finished with them.
This has to be a really long-term solution for us. Given the question-mark over whether our nuclear deterrent is really independent I personally would like to see the service life of our current SSBNs extended whilst we put together our own genuinely independent nuclear deterrent. Long-range nuclear cruise missiles ought to be within our technical capabilities and financial strictures, and launchable from a larger Astute force and some new-build Victors and/Buccaneers...............