Get "Here" (was Nokia maps) from the Play Store and download the maps via WiFi, then use the Offline mode to reduced mobile data use to zero.
Google Maps will use the most data.
The 2 apps that have the maps stored on your phone don't need any data,you could switch your data connection off and they will still work but Google Maps uses data to constantly download maps as you travel.
As mentioned above,Here Maps is an excellent app and if you have access to wifi you can download the UK map to your phone and it will need no data to operate.
I used Google maps the other week to drive a 660 mile around trip. It used just over 800mb of data
Normally I stick to CoPilot although it's paid for but does offer offline mapping. Not quite a smooth looking as Google although it does give speed camera warnings. Played with Here Maps but didn't feel quite as nice.