Final chapter:
Busy day yesterday, no time to post updates.
Full fibre install (FTTP) promised by BT/OR yesterday, morning appointment, many texts, e-mails and phone calls in the previous few days confirming the proposed activity.
As no show by 11:00 am, called the engineers mobile number which had been provided yesterday, he responded and advised he was completing another job and would attend at 1:00 pm which he duly did.
Turned out to be two OR sub-contract lads who attended, advised that with UG fibre installs in this area OR engineers invariably have to call in the "heavies" anyway for path crossing, flag stone removals, digging etc. so makes more sense to send out a 2 man team at the outset.
The sub-contract lads complete 4 UG fibre installs per day and are paid on job completion only, they work around the 4 proposed installs logistically by area rather than appointment slots which tends to make a bit of a farse of the morning/afternoon slot allocation I suppose!
However, they were good lads and did a very neat & tidy job.
Drilled from the recently installed footway Toby box which was right beside the CBT chamber, under the garden wall, usuall shallow track across the front garden to the designated entry point, they were absolutely delighted with the duct I had provided under the concrete path and the conduit through the wall to the double box where the ONT enclosure was mounted, couldn't believe their luck, offered me a permanant job.

Fitted a Nokia ONT, advised their stock of Huawei units was exhausted and Nokia's now standard.
Fitted the ONT enclosure perfectly after removing the 3 small rear spacers as advised in the instructions.
The pre-fitted ethernet cable from the back box worked well causing no obstruction to the fibre run.
Gave up the idea of PoN supply to the ONT as the splitter was a bit too big for the back box, may investigate a small plug top type UPS unit for the ONT as the Hub is already running on my main UPS unit.
With the fibre BB up and running noted that my Zen FTTP service was still active, had left modem & router active.
After about an hour, the FTTC router dropped PPP session.
After about another hour the FTTC modem dropped synch.
The BT supplied digital phone sprang into life some time later having been previously paired with the Hub.
BT confirmed by phone that my LL number transfer had been completed.
Plugged my Gigaset DECT base station into the Hub and all handsets worked perfectly.
Still have a dial tone today on my old hard wired phone, BT line test still works but reports another circuit number (not mine) on same exchange?
Zen informed me by e-mail that the transfer of BB & phone service was complete.
So, good result all around, happy with the outcome.
Apologies for the
very long post, hopefully will be of some interest to future FTTP migrants.