I feel for you as I went through exactly this situation. The key is that you live in block of flats and I'm guessing, from my experience, that those with fibre around you have fttp.
If that's not the case, them I'm at a loss as to why you 'can't' get fibre. If it is the case, then you probably face a long haul to get your landlord to agree the installation of fibre, which involves signing wayleaves, etc. I live in Cornwall and our flat (we're no longer there) was a block of four dwellings, with each owner a director of the management company. This latter factor made the signing of the wayleave a straightforward formality, but can be a total showstopper if your landlord won't play ball.
I had to get Superfast Cornwall involved, but once I had got their attention, they were very helpful, and we got fibre run into the building in due course. You will need to contact your BDUK authority to get the equivalent service.
I suggest that as a start, you use the Openreach Broadband Availability Checker, address already provided, click on the 'Address Checker' link and enter ONLY your post code. This will give you a pulldown list of the addresses from which you can assess the fibre availability in your locality. This is very useful evidence when when making your case to your BDUK authority.
Hope this helps