You shouldn't be doing a booklet in Photoshop - period!
It should be done in InDesign.
If you already have it in photoshop - then you can make each file a PDF - then use Acrobat to combine the PDFS.
Acrobat has a Print Booklet feature.
If you really need this done in a hurry then hire a professional who knows InDesign to complete the task for you.