A primer is a book that introduces a subject. Whether you want a strictly secular atheistic approach to cosmology, or a religious approach, determines which source you might want to go with.
The Wonder of the World, 2003, by Roy Abraham Varghese is a good introduction to cosmology and other aspects of the physical sciences, including evolution. Varghese is a theist and this book was influential in turning the famous atheist Antony Flew toward God before he died.
Another good source as an introduction is Gerald Schroeder’s The Science of God. 1997. In Chapters 3 and 4 Schroeder, a physicist, makes an interesting attempt to find a correspondence between the the history of the universe and the seven days of Creation in the Book of Genesis.