Technically it is possible to write a bot for getting those information, but sooner or later you will either hit a legal issue or a query limit (cf. Section C of 118118 terms on bulk downloads).
For bulk operations I would recommend setting up your own instance of the OpenStreetMap server with Overpass API, where you can find the necessary information.
First you may test the API on existing instance (the requests might take several seconds to complete, even for small areas), although using them excesively will be considered bad manners by the community (http://wiki.openstreetmap.org/wiki/Overpass_API#Introduction):
Have you come across Plus Codes? The aim of the whole thing is essentially to provide an "address" to everywhere, regardless of whether or not there is an official street address there.
As far as adding the address of a place to Google Maps, you can use this to create a private place quite easily. First, find the spot on the map. Then, either using the Google Maps app, or the Plus Codes Map, find its code. For instance, I'm going to select the tip of an island on the St. John River:
Note the full code in the sidebar: 87RGQ95V+JP. It can actually get even more specific, like ...JPX, which is down to individual meters, I believe. But this is specific enough for me.
Back on Google Maps, go into the menu and select Your Places. You should be able to set your "Home" address with the Plus Code.
Go ahead and close "Your Places" and view the map: your home is there!
Another method: In Google Maps, simply search that same Plus Code. When the search results pop up, click the option to Add a Missing Place. Name it as you like, and supply the Plus Code again in the Address box:
And there it is! Huzzah!
Note that depending on the category you choose, this may or may not be visible to other users. You may be able to add the locally-used address to the "Name" field, depending on its length. This new place will also be added to the "Your Places" tab.
Best Answer
From the Google Maps help on how to Fix an error on Google Maps: