There might be a database issue here.
Using the BT Availability checker;
Click the Address Checker option and search using your postcode (E14 9HW) and building number (37) will show quite a few of the flats can get FTTP and quite a few can't. The main building address can't get it.
However, Royal Mail has one other postcode for this building - E14 9HB. That doesn't show as many flats but it may turn out that there has been another postcode used as well.
Your ISP may have to do a bit of detective work with the BT Openreach address database or even raise a case with them to get an explanation.
These are my own personal views and do not reflect those of O2