On the works to install cable in your area, there's a few things to be aware of. Re the Council - any road/footway/footpath opening/excavation has to be notified to and then agreed by the local authority in your area - this is all part of the New Roads and Streetworks Act. The council is there to ensure the contractor complies and carries out reinstatement accordingly. As to why OpenReach didn't have the council there, well, of OR were just accessing existing infrastructure, their current ducting via accessible manholes and using where the current lines follow, there was no need to provide notice. They would still have had to notify on the works.
Why where the contractors there with machinery - what is usually the case, across the country, is that BT etc will restrict access to their existing ducting as it's there infrastructure and deregulation just means access to a certain degree for some companies. In your case, sounds like the only option was to install new ducting and line. So, "heavy machinery" much easier than trying to dig up tarmac with a trowel.
WiFi - this can of course be problematic and depends on so many factors, not just a transmitting router and the fabric of a property. The devices you use, their network protocols have to be compliant too. Talking about speeds etc.... there's such a mix of protocols. A PS4 won't even touch wifi6