That's surely totally different - it may not 'cost that much extra' if one is adding it on to an existing application/notification but, if it were not part of another project, they would, AIUI, usually charge at least what the notification fee would have been at the time, often up to double that figure (i.e. potentially 'hundreds of pounds' in total).John, I would get the certificate done retrospectively if it meant an easier sale; it doesn't usually cost that much extra. I had to do it for a new downstairs toilet recently after that 'final inspection' where the supervisor came along and asked who did the electrics. I hated parting with £62.50 (after 50% discount) for no further visits and a completion certificate, but it was that or not get the whole thing signed off.
I would have to be very desperate to sell to go down that route. Indeed, even then, it would be cheaper to do a deal with the buyer to 'split the cost' (i.e. reduce the asking price by half of what certification would cost) in return for him stopping asking for an LABC certificate. After all, that certificate is never going to be of the slightest use to the buyer!
Kind Regards, John