Notepad++ Display Printing Page Count
That really isn't the purpose of Notepad++. While a print preview function might be a good feature, Notepad++ is geared more toward helping keep code organized, differentiating files, etc.
If you want to see how many pages it is before hand, try printing to PDF first. At least then you have a digital version and are able to see how many pages it is. I recommend PDFCreator to do this.
Good luck!
You probably already have the Microsoft XPS Document Writer printer installed on your machine. You could print your document using the XPS Document Writer to see how many pages it will be.
Note: XPS documents can be opened by double-clicking or opening in Internet Explorer.