[Newshound47]

I think you mean Broadband not Wi-fi ......
But the UK  currently has only 1.3% properties unable to access less than "Decent Broadband" i.e. the USO
www.ofcom.org.uk 
that is smaller than the number able NOT to get PSB DTT TV!

That Document discusses how this will be reduced  - but does not mention that the Major telcos will offer 30Mbit/5Mbit?
as their USO product - which is ample for  streaming
i.e like the 97 % who can already  get better than this!  (comparble  with Freeview lite and Less than DSAT coverage)
Or the 75% on "gigabit capable" ( 52% Fibre rest Virgin DOCSIS)
But there is more work needed in Wales and Scotland ( NI has more Gigabit capable than England!)

But wiring equipment will improve things!!! and reduce Wi-fi interference

The accuracy is when it works. Plenty of areas have frequent slower speeds than advertised. Relatives live rurally and have fast speeds sometimes other times it is so slow even their Alexa struggles to work.