Most of what I have to say has been said already,but I will sum up what I think
You are aware of part p and the responsibility for Labc involvment,otherwise you wouldn't be enquiring on this site
You are to be commended for being aware, because the vast majority of the general public are neither aware of part p, or aware or concerned about IEE regulations electrical installation requirements for certification
You were aware of part p and should therefore be aware that it is your responsibility to ensure that work you have carried out in your home complies with its requirements
You could have used a non registered qualified electrician and informed building control, or the alternative method of employing a person who can self certificate for compliance with part p of the building regs by being registered with a scheme
Electricians who are trying to abide by this building regulation are very angry that lack of awareness by the public allows tradesmen(perhaps) who do not have the financial costs of complying ,to be undercutting the law abiding registered electricians, and householders who employ these peolpe do so on a lower cost basis only
If the guy was registered then he had 30 days from completion to notify the work to the Labc,so it would seem, he is either not registered, or he is in breach of his membership of his scheme providor
You say he is with the Niceic,this could and should have been checked by yourself, before deciding which of the 2 routes to compliance you were going to take,before the work started
If he is Niceic registered,their complaints procedure will make absolutely certain, that you face a long hard and mostly impossible quest for any resolving of your situation,they have a notorius catch 22 procedure that the public are not aware of
Your procedure in resolving this issue can be a number of ways
If the Labc are not aware of the work done,you could do what he vast majority of the country does,break the law by ignoring the rediculous notification rules of part p
You could involve the Niceic in the hope that it would miraculously be resolved that way
You could approach Labc and ask if another registered electrician can complete a periodic inspection report, that would perhaps satisfy them.it is an unacceptable route taken by building control,because they neither have the knowlege or time or inclination to want to be involved in proper procedures of complying with the law
You could then have a regularisation certificate off building control that will satisfy part p
All in all.it was your responsibility,you didn't comply.you now have a problem with the standard of work
the standard of work could still be poor and building control satisfied with procedure,but the standard of work is probably irrelevant,you did not follow procedures,you are the guilty party
Hyperthetically,because you had this work undertaken without permission, and the only certifcate that building control should accept, is an electrical installation certificate (EIC). then because of things like routing and installation methods of cabling,no one could issue this certificate for you, other than your installer,if that were the decision of building control,then yes you would have difficulty displaying the cabling to them and they could ask for cables to be displayed,hence the "rip it to bits possibility"
That will not happen,you need to ask Labc what procedure you can take to rectify your own mis demeanours
In defence of yourself,its a sorry state of affairs when the general public look to these cowboy tradespeople sites, before the competent person government registers