The worst thing that could happen would be that the inspector will insist on a registered spark doing a Periodical Inspection Report (PIR).

If that shows up any major problems (level 1) these would have to be rectified. If the work was not done to the labc's satisfaction then a, I think it is referred to as a distress warrant would be issued by the council where all the works would have to be removed and the whole lot redone.

Never ever heard of it ever happening anywhere in the UK regarding electrical work. I have come across it on new builds where no planning was authorised - as in the case of a very well known MP once in Kent, say.

I would not worry about it the chances of labc typing up the loose ends is just about zero. Something MAY come of it in the future when some future buyer of the property solicitors does a search but hey there will be plenty of those.

The man in Revenues and Benefits who deals with your council tax is highly unlikely to even know of the existance of any other department outside of his own directorate, likewise with building control. So no, I wouldn't worry about it.  

Note that you don't have to submit reciepts for work done. You just have to prove the house was unoccupied and unfurnished. If you can do that another way then that might save a lot of agro.  Was th furniture put in storage? Get a reciept for that. Was the meter read before and after? Removal mans bill? That sort of thing should be sufficient.