To replace an item like for like does not come under Part P. To define like for like is rather gray and many consider to replace a window fan with another window fan is like for like even if different make. There is a like to Part P in the projects section.
As to working out what a popping noise well my wife watches Medium but I have not worked out how to do it yet. Could it be the shutters operating?
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!