Hi Nobby, welcome to the forum.
Touring caravans usually have two electrical systems.
The 12 volt system which powers the water pump, toilet flush and some lights.
The 12 volt sockets are normally round, like car 12v sockets and the 12volt system runs off the leisure battery which is charged by the onboard charger (230 volts) or the car 12s socket on your vehicle towbar.
If the leisure battery is fully charged it's possible to use your caravan off grid using 12volt power and lpg for the fridge, water heater and heating.
The 230 volt system powers the three pin sockets, the onboard battery charger and some of the interior lighting, plus the fridge if on ehu (electric hook up)
For the 230 volt mains electrical system to work the caravan must be connected to an external power source, on caravan sites normally a ehu bollard via an ehu lead.