The reliable way to hire a tradesperson

I have just had my bathroom done and changed my lights switches from a pull switch to a wall mounted switch just outside the bathroom. I also added LED lights to the niches. Does this work need an electrical installation certificate ?

I’ve recently had my garage converted which involved new lights and sockets throughout the existing garage and also having a new consumer unit fitted for all the new and existing electrical connections in the house. I’ve received my electrical certificate and under description of installation it states ‘garage conversion socket/lights’ and under extent of the installation it states ‘sockets/lights’. There’s no mention of the new consumer unit anywhere on any page of the certificate. Please could somebody confirm if the consumer unit install should be listed as well as the sockets and lights install? Any help very much appreciated

Hi, I just moved in a new house and the room above the garage is always cold. I was thinking to put some kingspan straight on the plasterboard. I don't want to take down the plasterboard and to put it between the timber, that being too much work. It is affecting in any bad way the ceilling if I do it like that?