Hello Seand
I appologise for being a bit abrupt.
The picture you have sent is as you suggested for the 230V mains input to the caravan.
This does raise the question of where the water inlet is. The caravan definitely has a Carver Cascade 2 water heater located just in front of the wheel arch. From the pictures you have supplied your caravan does not have a Carver Compact pump system. This suggests you might have an inboard pump, and the grey round port may be the hose connection point for an external water container.
I still believe you would be best trying to find an experienced caravanner who can go over the caravan with you to get to grips with what you actually have. It will be far quicker and more conclusive that trying to resolve all the of it over the internet.
I also believe bearing in mind the age of the caravan, and your uncertainty about it you would be wise to have the whole caravan checked over by a professional function and safety.