to get 100% connectivity that will be a hell of a lot of road digging.
If the existing cables are on telegraph poles or in ducts, then there's not so much expensive digging required, which makes a big difference. You'll have to hope one of these two apply, because with all the madcap, unwarranted, and economically unjustified infrastructure schemes that the government have signed up to, there not much chance of finding enough people capable or pouring concrete or laying tarmac...
A partial list includes Hinkley Point C, Heathrow R3, HS2, Thames Tideway, HS3, CrossRail 2, Moorside, Wylfa B, Oldbury B, Bradwell B, Sizewell C, not to mention many tens of billions on water AMP6, Ofgem's c£40bn of RIIO programme's, billions on some notably unambitious road schemes, token flood defences etc, and that's before we consider the impact of government promises of new towns, and 200k+ new houses built each year. That little lot totals something around half a trillion quid, over and above the existing asset renewal needs.
Now, with vast budget and balance of payments deficits, rising private sector debt, yet investment plans formulated using the "kiddy in the sweetshop" model, you really have to wonder why the Labour party are so busy whining about "austerity".