FTTC speeds will be good until take up increases. although cabs are live it doesn't mean everybody in the catchment areas has jumped ship from ADSL.
This is the same issue for any technology, there is only a finite capacity, "unlimited" is an unachievable target in reality as it is with ALL resources.
Fixed wireless is a fast evolving technology and capacity is increasing regularly and pretty much the only issue is capacity.
FTTC on the other hand degrades with many variables , line length and quality , crosstalk, radio interference (especially overhead phone lines).
This then includes backhaul capacity and how much bandwidth the ISP the other end has committed to paying for from BT. As these costs are fixed per mbits/sec then ISP's are obviously keen to have that pipe as saturated as possible to maximise the return.
These are the same issues ADSL had, just with shorter distances and greater chance of "unlimited abuse" contention effects.
Your work with 100 metres from the cab will be unlikely to suffer some issues at least, others on the same cab may not be so lucky later.
We at Kijoma are currently field testing new higher capacity equipment and will fit this to live networks once testing has completed. I suspect Vfast are doing the same.
We have done this 3 times before over the last 10 years, replacing entire networks and client equipment. It is not cheap but was necessary to keep up with demand.
No tax payers/state funds are being used to do this either, it like all non parasitic companies out there is paid for by the profits from existing customers and they will be the first to benefit.
The ~£2Bn of state aid to BT, although producing results ,will eventually come back and bite , just as it did with ADSL ~15 years ago when all the eggs were put in that basket.