It is better to use a desktop publishing program to produce books/booklets. You may be able to find a free offer for an old version of Serif PagePlus. It used to appear on magazine cover discs. Printers generally prefer pdf files.
It allows you, (amongst many other things), to print a document as a "booklet". It automatically sorts out the page arrangement so that you can fold a document printed on A4 paper into an A5 size booklet.
If you dont pay for it it leave a "printed using Fineprint" mark on each page.