You don't have to worry about Office 2011. According to
Roaring Apps, it works just fine in Sierra. As an addendum to this, I use Office 2008 and it's working in Sierra as well. Roaring Apps is a good place to check compatibility. For the few apps that weren't listed there, I contacted the developers for info before I went for Sierra.
Do you know someone who has a broadband connection and could put the installer on a USB drive for you?