i created a document, a banner which is 4 A4 pages size in total but one complete page in indesign. I now want to save the document as four separate A4 pages as my friends dont have a banner printer. Is this possible or will I need to recreate the banner onto A4 pages?
You can make a new 4 A4 page file, turn off page shuffling and drag them together into one spread, then copy the art and paste into the new file, but this probably won't help you very much because it is going to leave you with white borders around each A4 page when printed so you'll have white stripes between sheets and a white outline on your banner.
Instead, print the banner as tiles with some overlap and assmeble from the original file. You'll wind up with 5 sheets (or more likely 10 to accomdate the marks at the top, unfortunately), not 4, because of the overlap.