There are all sorts of reasons for delays. I don't know if you live in an individual house or a residential building. Blocked duct is one thing and a wayleave agreement is totally another. Or it can be a combination of factors that play into it.
The date might be pushed back for you between July to October 2026 but the problem is that the FTTP Map is a little generic as it will either show no plan or plan between now and December 2026. That's the Openreach ambition to get 25 million premises passed.
https://www.ispreview.co.uk/index.php/2024/04/openre...
NOTE: BT are investing up to £15bn to bring FTTP to 25 million premises by December 2026 (80%+ of the UK) and they aspire to potentially reach up to 30 million by 2030 (c. 25-30m).
Not everyone will get it by December 2026 and some premises might even get it earlier even if the map doesn't show planned! Others will be pushed until 2030.
For example, in this Openreach Fibre Cities Map for one particular exchange Stepney Green in London will show that the build plan is for the future and not right now. Postcodes within that exchange have no FTTP plan. Yet ironically recently one residential building got Openreach FTTP go live and taking orders within that very same exchange that isn't planned at all! That building is Winterton House in London, Shadwell area. It is a social housing and already has multiple FTTP network providers from Virgin Media, Hyperoptic and Community Fibre. I do not know the logic behind Openreach building FTTP there as well, but they probably know better than I or most people.
And there is also a case of economical viability. I still do believe Openreach tend to cherry pick areas that already have Altnets as they don't want to lose existing FTTC customers. Areas that have no choice tend to be delayed as Openreach know that they'll have them kept as customers using ADSL/FTTC/G.Fast by default.
Each case is individual. Even though I may live within a few minutes walk to the City of London that doesn't necessarily mean I'll get Openreach FTTP quicker than someone else in a rural area that is supposedly deemed less economically viable. Because like I said before it may be that Openreach are very much interested to build FTTP but the management is the obstacle for this agreement. Or in other cases the management is interested and very much happy to grant wayleave but Openreach is not interested.
Most of us don't know why some exchanges are unplanned that are very close to another postcode that is under a different exchange. Maybe Openreach want to build area by area at a time and then move on once those are complete.