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.