Although the book isn't officially published until mid-January 2016, copies can be pre-ordered through booksellers online right now. The eBook version is, however, widely available already and is only £4.99!
But why wait until January for your paperback copy? You can get one right now direct from the publisher, or if you're in the UK a signed copy direct from Mike.
Just click on the 'BUY' page - all the options are there