Hi,
Have you tried using a different web browser to download the manual patch?
If you are still unable to download the manual patch because of the 403 error, you can check out the following thread for a possible workaround:
http://forum.thesims3.com/jforum/posts/list/693317.page
I've tried downloading the patch through the launcher but every time I do it says http://www.sims3.com/launcher/patches/447287726(paused)