One of the beauties of UK touring  caravans is they are  designed to able to be used off grid with no 230V  being  available.    This is why you have diversity  of energy sources for the fridge,  water  and space heaters.  You  may  not  be able to use the 230V ac appliances,  but  you  do at  least  have the means to  keep  the fridge working,  keep  warm, heat water for washing,  cook food,  and boil  water  for hot drinks all by using  the gas.
Other functions such as lighting and entertainment can be managed with 12V systems.  It  helps to have some form of  of grid 12V charger, which  can be achieved without  a portable generator by  using  solar cells.
You  do have to  recognise you  need to  be aware of the  limitations of each of these systems and exercise good energy  management,  Only turn items on when you  need them,  and also turning them off when you  don't. Only  using  as little water as needed. You  may  need to plan a little further ahead when for example cooking,  as caravan cookers do take longer than their domestic counter parts.
You  may  not  be able to  watch TV as long  as normal becasue of the limited capacity of the caravans battery.