The text would have to be aprt of the puzzle pieces layers...
But the text needs to be on the back of the piece so as the piece tumbles we see the picture on on side and the text on the other.
If you want to stick with your original concept duplicate your puzzle pieces so that each has a mirror image. The easiest way to do this would be to flip the entire image horizontally in Photoshop. Save the copy as a different file add your text to each piece, then use the first psd and all of the layers for the front and the second for the back. Then you duplicate your text layer 40 times and sandwich each text layer between a puzzle piece and use layer clipping in Photoshop to mask out all of the text except the portion over the puzzle piece.
A much easier solution would be to create your text layer either as a PSD or as a text layer in AE, create your front puzzle image in Photoshop then apply Effect>Simulation>Shatter and choose Puzzle for the shape. Use the Front image for the front Texture, the Text image for the back, animate Force 1 position, depth and radius, and set the physics to make the puzzle break up into pieces and fly off the screen. You can use AE's camera to get your 3D camera move on the shatter layer.
I know, everything is backwards. You want to have the puzzle pieces fall into place to spell out your text. That's also an easy fix. Nest your shatter comp inside a new composition or select everything and Pre-compose then apply Layer>Time>Time Reverse Layer (Ctrl/Cmnd + Alt/Option + R) and you're done. The advantage of this technique is that the puzzle pieces can be extruded. You can even set different layers to map on the sides.
If you want a custom shape for your puzzle pieces just create a custom shatter map in Photoshop with each puzzle piece a different color and use that image map as your Custom Shape Layer. The whole process will take you about 10 minutes. This took me 3. The text is text from this post pre-composed against above a gray solid.
AE layers are one-sided. As Rick suggested, you will have to use an effect that actually adds dimensionality to the layer and texture it accordingly or use an effect that blends between different versions of the layer based on which side is facing the camera as per this example:
Many thanks for your ideas but I think it may be a bit beyond my skills at the moment. I was hoping it might be as easy as the Matrox cube effect that I used to use with earlier versions of Premiere. One added complication is that the jigsaw is a real one and we go to live action with people taking it apart once it has been built. I will re think my ideas and do the text in a different way.
Once again many thanks
Shatter is easy. Here's the CS6 project file using Shatter. Just change out the background picture and the text layer. Then render the Render This Comp composition...
Please just spend a little time with the comp to figure out what the controls are doing.