Ebook: The First Three Minutes: A Modern View Of The Origin Of The Universe

This is a well written book for those unitiated in physics and cosmology. It was written before the Big Bang theory was revised to include inflation so some of the concepts are already obsolete. It is a good starting point however. I would recommend following it up with the Inflationary Universe by Alan Guth or The Universe in a Nutshell by Steven Hawkings.