Thanks for the reply. Always best to start with the obvious ones mate.
3 yes's.
However, in spite of not being able to access the public folder through the bog-standard network folder, I have now been able to do my rsync using the "purps@192.168.80.1:your/path/here" business. I also discovered that if you want to actually browse the folders on the core, then "connect to server" in the main menu in ubuntu is the way to go - simply type in "192.168.80.1" at the top, give it a name if you wish, and away you go.