Update on the OR Engineer visit: The broadband connection was up when he arrived, so he firstly used a device and connected it to the fibre cable in the house and it found a fault.
He then ran the same test from the grey box on the outside of the house. Next he tested from the underground box at the end of the drive, testing the fibre cable from the box to the house. Whilst he was checking that cable he told me he cleaned it with a device (not sure what it was called) because apparently it had been disconnected whilst fixing next doors fault. He tested again the fault had been rectified.
The broadband connection has now been stable since he left, which is great news. Thanks for all your help 🙂
