The Severn "Tidal Lagoon" project has been dogged with controversy for some years. I doubt it will ever see the light of day.
The fact that there only a handful of tidal power stations in the world leads me to believe that they are either not terribly practical or economically unviable. It sounds a great idea - regular and reliable free energy. That just makes me wonder all the more why there are nor more of them. Since each one will slow the rate of the Earth's rotation perhaps that's the reason there are not too many!
I'll have a look at your other question after I've had tea and bikkies, Khandro.