Update 28/10/2018 approx. 02:48 - The issue seems to no longer be present. Or at least from what I have checked.
I don't think this is the most appropriate place for this, but please move as necessary.
There seems to be an issue with both the DSL checker and Openreach checker.
I actually freaked out because when I checked the number for a BTW line to the premises, it was essentially saying it is not a BT number ("There is no data available for this number") on the DSL checker. The reason why I was freaked out is because I am switching ISPs soon and, even though the correct CLI was provided and my ISP notified me of the migration, I was worried that they had somehow got the wrong line!
Anyway, I soon figured out that the case was not as I worst feared and it looks like there is some database issue - perhaps something to do with the "falling" back into non-daylight saving time? I checked a few addresses, at least in my county, and they all returned the same thing - "Your address has been successfully matched; however we cannot determine ADSL availability at this address. Please try the Telephone Number or Postcode Checker".
Checking the postcode returns ADSL estimates just fine, but I haven't tried anything else or with the BBEU.
Openreach 'When can I get fibre?' essentially just returns that the "number or postcode was not recognised"
I was actually hoping my dreams had come true and G.fast would appear as available pretty soon! But we know it is no more than a dream.
Anyone else can confirm?