Thanks very much msjw. Hopefully someone on here can figure out how to get line stats out of the modem; I know someone that works for openreach so I'll give them a call tomorrow and see if they can put me in touch with some knowledge. I'll try and update the thread with some information.
No problem - I'm also hopeful that we can get stats from the modem somehow.
I can also confirm that I can connect my machine using a PPPoE session direct to the modem. When I do that I get the my static IP assigned to me (and default gateway set to my static IP too). I can't seem to find more info on how to access any modem interface when I connect via PPPoE, though.