One BT issue that bears a separate comment.

BT determines what service it can or will provide to a specific address, irrespective of that the advisory sites might report.

On more than one occasion that I am aware of, BT has advised a customer that a full broadband package is available in an area and to their specific address.

However when the OpenReach engineer turns-up to do the cable installation, they occasionally decline to do the work, despite the BT commitment.

As best as I can determine there is still uncertainty about certain types of installation, particularly if a building has several disparate homes in it. As an example if a building has been converted into say four flats, OpenReach seems to have a long term problem because it has not yet have a reliable solution for that configuration.

I have no insight or reports how other providers may or may not deal with this issue, but it is worth being aware of this BT issue if you are moving into a multi-occupancy building.