Thought I'd come back and update on what happened...
BT started getting quite insistent on updating me to FTTP as I do need to have a phone line and they are heavily pushing Digital Voice. So I thought OK, lets play the game and see what happens as if nothing else, it would mean I could investigate mobile 5G router solutions were they to be needed in due course.
Appointment 1 - Openreach sent a contractor who had been doing the job for a couple of years and according to what he said, and had never come across External Insulation (EI). Pretty much as soon as I said you can't put ladders up he was on the phone to his control people who fed it back to BT / Openreach as a job needing "additional work".
We did have a conversation about what I said was needed for the install to be acceptable and he said not possible.
Appointment 2, 3 weeks later
Clearly the complications were reported back correctly as this time I got an Openreach chap.
He was a lot more aware of EI and after discussion he said he could run it under the facia by calling out a cherry picker, then in the gutter, then down a downpipe at the side of the house and use the existing hole for the current FTTC. This did mean 1 new hole through the EI but I made sure it was siliconed which I'd found was an acceptable way to stop water ingress as advised by EI fitters.
The Openreach chap was much more amenable about things than the contractor and so with us both being a bit flexible, I now have FTTP Fibre 2 and DV with a newly supplied Smart Hub 6 which I renamed to my previous Hub SSID and everything came back to life.
So hopefully that's me fibre converted for the foreseeable future and a good outcome for both me and BT.
It also means if I choose to move from BT at a later date (I've actually just renewed at £24.99 for BB and £3 for DV as in my area its a good deal), it's going to be simple for any new provider to take over the service.
If anyone else is in a similar EI situation, do push to get what you want (within sensible limits) as in my case, Openreach did bother to listen and work with me to a satisfactory conclusion.
