The firmware/OS version you have is lower than what's needed for Update 2. For example if look the Denim OS version for Austrian 735 its listed as 8.10.14234.375 with Firmware version 02040.00021.15063.02002. This is a higher OS version than what you have, I am not sure what new features it brings but it definitely enables Update 2 via Windows Insider. You could either wait for MS to release the OS/firmware update for the Belgium variant so you can get Update 2 via Windows Insider or flash to a ROM w/ that version. Again if you do not know how to flash ROMs and stuff I would suggest not doing it.