ok provided that your 41.8GB of free space is on the C drive then the only other thing i can think of is its an isue with the language packs.
Go to Start, Control Panel, Region and Language > Keyboards and Languages > Install/Uninstall Languages > Uninstall display languages. Then click EVERY language there, except English. Then uninstall. This process will take about 1 hour, maybe longer.
Reboot after this and go back to your Windows update and try again.
If it installs successfully you can then return to control panel and re-add all the languages if you wish.