P
Paul_C
I will be contacting the local building control to hear there take on the matter - and will relay information that everyone has provided!
You can't rely on them to know the rules properly either, but my bet is they'll tell you it's notifiable because of all the guidance notes etc. already discussed above (and because in light of that they're not going to miss any opportunity to try and take your money if they can).
If you have any thought, even the slightest, that you might want to do the job without notifying, then I would strongly suggest that any inquiries you make to the local authority you do so in a general, anonymous fashion which cannot identify you personally or your address.