The first thing is to draw up a list things you're not happy with, and then discuss it with him. Is he emigrating straight after the job's finished, or just intending to go sometime this year. If it's sooner rather than later, then you need to discuss the "warranty" because he's not going to be around to rectify any problems. How long is guaranteeing the work for, and will he be around to fulfill his obligations. Depending on the answers, you possibly get another builder (you may well have to pay him) to assess the work, and what it'll cost to put the faults right. If there's draughts coming from the spotlights, that implies the holes aren't the right size, or the spotlights haven't gone in properly. Who signed the electrics off, and do you have the certificate for the work. Obviously, you don't make the final payment until you're happy with the work. Let him sue you if neccessary.