There are ( roughly) four ways to get internet access to a property
Mobile phone / cell tower / phone mast to a dongle or 3G/4/5G router/mifi device - as you have/ are already doing
WiMax ( or fixed wireless access) usually found in rural areas and Hull, where you have an antenna that looks like a cross between a TV aerial and a squashed satellite dish where the internet is provided form a remote transmitting/receiving site
Satelite, an expensive option suited for areas with no other option
Fixed line connections , where the internet is delivered by a line that runs over or under ground .
in the case of Now they use openreaches copper based network, over which two services are available : internet and voice. the line is assigned an identification number that is the same as what you would call a land line number.
The voice service is on a take it or leave it basis, if you dont use it or dont want to use it then you dont pay for it, if you want to use it then you pay for it by call charges or by taking out a package/subscription ( evenings/weekends/anytime etc)
One thing you may need to check is with it being a new build ( ie within the last 5 - 10 years) is what services are available ? i have some new builds near m, one of which is virgin media only no openreach, the other is openreach FTTP ( full fibre only) and the other is persimon homes "fibre nest" only, and on those three you can not get now broadband.
In the case of persimons fibre nest, or virgin media exclusivity i would stick with the three mobile solution, if openreach fttp is available then i would look at the options
