Not sure what a shower mixer inlet tap is. Do you mean a bath shower mixer tap or a shower mixer valve? If so, they probably will dork directly, but some need restrictors in to reduce and balance the mains pressure. If you know the make and model, you may be able to Google the installation manual.
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!