Just a final update to say that Openreach carried out the remedial work yesterday and an I'm back up and running.
They also sent an engineer out to my house to verify that everything was working properly, which was appreciated.
A couple of neighbours had also had it installed while it wasn't working, so this may have helped speed things a long a bit.
I'm really happy with the FTTP connection and its a massive improvement over the VDSL service, delivered over half a mile of copper, that I had before.