There are 4 UK mobile UK phone networks, try entering the postcode into each networks coverage page and see what comes up. One might cover the area.
Due to poor BT service I've been on mobile broadband with data only sims for many years for a fraction of the cost of a landline service. The online coverage maps are not always correct in the real world though. One option is to get a PAYG or a 1 month sim on each network to try in a mobile handset. Once you have that information buy a mobile broadband router (unlocked so you can change networks and one of the better ones). There may be limitations using a MVNO sim instead of one from the main network but a might be to OK to start with to see how it goes. Some do not allow access to all the available bands.
Look at cellmapper.net to see what masts are in the area of interest. Use the menu to select the network.