Are you just creating pages for PDF?
If that's the case, you can just create the first page, save it as your template.xcf
Then just open it in GIMP edit it to your liking, and save it as Page 2.xcf, and Page 2.png, then just keep doing that until all your pages are completed.You will then have a xcf and a image file of each page.Then just create a PDF from each image, and splice them together.There are free programs that do this, such as PDFsam ...PDF Slice And Merge.This way you will retain a xcf for further editing if need be.
If you are trying to save it any other way or build it any other way, i am not sure how to do that.
There are programs that are free also that you just create each page and make it an execute file.
You would have to Google for those though. =)
Hope that helps..