Yeah, they're all connected.

If it is the case that all ports on CBT are allocated and demand is such that everyone mapped to the CBT has taken FTTP , then ( unfortunately ) more network build would be required to get more capacity to your pole , and it’s possible that the splitter is at capacity too, so not just a case of new CBT from the existing splitter,
I believe there is a formwize on the OR website for consumers that cannot order FTTP but neighbours can , that ought to get OR to at least investigate, if there is a notes field you may want to mention the building is new , built in the grounds of an existing property rather than it was missed off plans from the outset

Thank you! So I did a bit of investigating on the BT Wholesale checker...

21 out of 54 properties on our close show as FTTP available
8 out of the 21 show "1 Stage" under "FTTP Install Process" - the rest showing "KCI2 Assure" most with "potential Line of sight problems"
5 out of those 8 properties have an active FTTP service/ONT installed

8 would make sense as I believe the one CBT at the top of the close has 8 ports... and I guess that would mean the splitter has capacity for (at least) 21 properties?

I'll do that now, thank you!

Each splitter can serve upto 32 connections.

One cause for "potential Line of sight problems" is if you have overhead mains distribution in the area.

The Openreach form mentioned by others is https://www.openreach.com/forms/fibre-broadband-avai... although they have separate pages related to new build.

Ordering a copper phone line service first is a hack to get the Openreach database propulated with a 'gold' address. I suspect that in some cases providers suggest this as it is less effort for them than using other processes to get the database corrected.

The splitter used by OR are 1/ 32 , but usually only 30 are allocated so 2 splitters would be needed for 54 property’s, , but obviously the PON area may take in more than the 54 property’s,
The chances are adding an extra property isn’t going to require anything more than lighting up an extra CBT port , but if a new CBT were required , it’s not just spare splitter fibres but a spare tray in the splitter node as well , but that’s probably not going to be an issue.
When the new property shows as having FTTP availability, either single stage or KCI2 ( keeping customer informed ) that is when your ISP can order service.
21 property’s out of 54 showing as having FTTP suggests the build out is incomplete, if the area is a mix of overhead and underground and the underground property’s are non ducted buried cables , the overhead property’s may show up first as available , as they can be easier to deliver , if it’s all overheard , it would be odd for some to show availability and others not , however , every PON area has a boundary, and it could be some are on the wrong side of that boundary

This is all making a lot more sense now, thank you!

I have filled out the form, hopefully Openreach will just correct the database and we can place an order. Its good to know that there shouldn't be much work required to get the property connected once the database is updated!

Thanks again!