This is "not simple" IMHO, as the physical length of text will be determined
by printer scaling, and the necessary position for the page break is also
dependent on the paper size. Word will not do true WYSIWYG layout for you, it
will always be somewhat adjusted by the printer.

From a document structure point of view (independent of code), inserting a
hard page break is almost always a mistake - OK, I haven't actually found a
situation yet in which it is the right choice.

If you are trying to control vertical flow in the document, use the
PageBreakBefore, KeepWithNext, and KeepLinesTogether properties of paragraph
objects. PageBreakBefore set to true ensures that the paragraph to which it
is applies is always situated at the top of a new page, regardless of the
pagination or positioning of the preceding text or objects.