A couple of pretty glaring errors in there.
First, on the sites that haven't yet got development plans.
Moorside IS Sellafield (the sites adjoin). The second site after Hartlepool that hasn't got a planned development is Heysham, and that's mainly because its the most space restricted of the sites. It'd be hard to fit a modern twin unit LWR station until one of the existing stations is at least part cleared.
Second on Oldbury. It has GDA clearance already, as its to use the same design as Wylfa (GDA stands for GENERIC DESIGN Approval)
There's another point, too. I think you're being rather pessimistic on GDA timescales - that average is rather inflated by the fact that the process on AP1000 was put on hold for three years when there appeared to be no likely builder. ABWR too about 54 months from end to end, and HPR1000 is scheduled for about the same.