You are correct in that the first estimate my the energy department was wrong. But the idea that it is all solved and that we can just build lots of it without having to worry is not a good strategy for a society in my opinion. Yes sometimes they sometimes make predictions that are wrong, but I still think that we should listen mostly to scientific prediction than anything else.
Yes and that the UK peaked at 28% is irrelevant ( EDIT: I used to harsh wording, yes it's a bit relevant but there are still problems with applying one solution to another place ) because they have different system with different possibilities. You can't implement the same systems everywhere since they have different conditions.
Maybe we can have almost exclusively power by wind in the future. But until then I prefer to listen to scientists and hear what they have to say.