Update

Been experimenting and seem to be getting random results, in the main the file sizes are around 3-4 times original size with embedding on.

Also downloaded a .doc file from 2008 not composed on my PC
3 pages of Times New Roman and some Verdana a couple of small tables and a smidge of coloured text here and there
File size 136kb

Changed setting to embed font (same 30kb TTF font file) as earlier
literally did nothing else, didnt even use a new font then saved file.
Now 1182kb

opened a new .docx put in some text embedded a font and saved, no problem nice small file of around 40kb.
re-opened and re-saved as .doc....file shoots up to 153KB,
turned of embed and re-saved file size back to around 40kb.

so it seems to be a problem with .doc format files .docx seems fine, trouble is i have to use this .doc format so others can read the document..

If nobody has any ideas i might try and reinstall see if that helps although i doubt it