Hi NicholasNg,
Thanks for your reply. I understand that you are trying to connect this laptop to a public domain and not the private network.
You are right in stating that it would require Windows 8 Pro or Enterprise. You can either upgrade your system to Windows 8 Pro or you can check with the IT department of your office to provide you with the copy of Windows 8 Enterprise on your system.
Once you have migrated to a compatible version of Windows you should be able to join the domain in office. If you have any further queries, please feel free to contact us.