Wind turbines scale much more easily than wave/tidal, both the size of the turbines themselves (much larger than a wave/tidal system could ever be) and where they can be located around the UK coast.
A diversity of renewable energy sources is sensible (nuclear, wind, biofuel etc), but wave and tidal are difficult to scale and have failed to deliver.
Based on what? With solar, we understood it was chemical science that would improve it. With wind, it was blade design, materials weight and durability, and generator technology. For tidal, what would improve that wouldn’t also improve wind? Improvements in durability, turbine, or generator tech would almost certainly also improve wind. Salt water will always be harder on equipment than air. Tidal forces are strong on large scales but on footprints similar to wind turbines, we aren’t talking about orders of magnitude more potential energy.