Yes, what you describe should work fine for casual personal use. But you have to test to see it it is good enough.
I just tested using LibreOffice Writer:
Saved a docx as HTML. (It had TOC and illustrations.)
Added that HTML to Calibre using drag-and-drop.
Converted to Mobi using Calibre. (Or epub if that is your preference.)
Added cover page and other metadata using Calibre.
As far as I can see it is mostly fine.
But this is not the recommended way to do this. It may not work at all as intended, because the formatting in Word may not always be exactly translated to HTML/XHTML. And there may be a lot of unnecessary stuff left in the resulting file, making it unnecessary big and perhaps causing problems in some reader software.
So you should take much more care when converting to HTML/XHTML. Some even recommend that you save the DOCX as a plain text and add all formatting again, from scratch, using a HTML/XHTML editor. And then create the ebook using that. Or use RTF. Or markup.
Last edited by Adoby; 09-09-2012 at 08:22 AM.