Do I need to have receptacles that I added tested before selling my home?
Unless the regulations have changed in the two years since I last sold a house...

No, the work you describe - provided it is indoors - is too minor to require certification.  

The buyer's surveyor may make a comment in his survey report that the wiring hasn't been tested for at least 10 years.  That might also appear in the legal Seller's Pack.  This could result in the buyer requesting a test, but that is down to them.

My understanding is that Scottish law is different.