zuluclayman

What actually happens when you try to print?
1) Is the image too big for the paper - only a portion of the image prints?
OR
2) Does the whole image print to a small size on larger (A4) paper?
OR
3) Does it print the whole image to A4 size?

If it is number one your image size is larger than the paper you want to print it on - when you print go to File> Print, then when the printer dialogue box comes up check the following: have you set up the printer preferences properly? selected your paper size and checked the box (or however your printer does it) to tell the printer to scale the image to fit the paper size you are using? What settings did you select from Photoshop?
If it is number two or three - make sure you have selected the paper size correctly in both Photoshop and your printer dialogue box.

If you want to check before you print - go to File menu and select "print preview" and it will show you what your print will look like.
If all else fails open the image (if you have flattened it into a jpeg or something similar) in Windows native Picture and Fax viewer and hit the print button at the bottom and it will open the print wizard which will guide you through the process - remember to set your printer preferences (paper type etc.) along the way!