Post codes are the least accurate way to check your cabinet.
Best to use either your phone number, or house number and street.
As for the original question, get all your neighbours to fill in the openreach and/or BT fibre expressions of interest.
Speak to your local MP too.
Good luck! I'm in the same boat in another new-ish development.
BT ADSL customer getting 1.9 Mbps on a new road / new build development
CAB not FTTC enabled, not part of the 66% commercial plan. Not rural - no BDUK funding
(Virgin Media nearby)