I did a blog on potential PV capacity in the UK here. There is an article from the Solar Power portal here which suggests the capacity is much lower (but still considerable). I looked at this again a few months ago and I’m sure I wrote a followup but can’t find it. The original area seemed to be plucked out of thin air with no basis in fact. The one given above is more realistic.
Excuse the lack of posts I’ve had problems with WP and updating it without breaking the site. More will follow.