D'oh!
The Ultrafast hub should definitely have "Ultrafast" on the front and come in a box marked "Ultrafast Smart Hub" (or Smart Hub X") - I can't remember and I'm not at home at the moment to check the box.
Maybe then that's the difference with FTTP and FTTC - I'm FTTC and was sent a hub with Ultrafast on it. Anyway, glad it's all working for you now!
The hub 6 for FTTP and FTTC are different, always have benn.