Or you can look in the forums and download to the PC and use Desktop Manager or other programs to load it.
I believe you will get the latest OS updates this way, and possibly not via OTA, because the people in the forums are constantly coming out with the latest OS released officially by ANY operator, and possibly OTA will only look for your specific operator's releases.
Besides, if you have the OS in your computer, I feel it's safer and faster to do it this way (Desktop manager).
The latest OS is almost always the first post of this forum. If you need help on this, there's a lot of advice in the forum.
There's several ways to do the upgrade, but the easiest would be dowloading Desktop Manager and the OS, installing DM and then OS, removing Vendor.xml file, connecting the phone, doing a backup (if you have third party aplications there's also several ways to do this) and finally using the DM to upgrade and restore.