I assume your Abbey is around pre2010.
All high energy appliances eg fridge, heating, hot water all use gas or 230V to provide energy. 12V will only be used for controller electronics if any and fans, all low power items. Lights maybe mixture of 12V and 230V, with only 12V working when off grid. Water pump is 12V.
Battery should start charging when caravan is powered by EHU (230V), may need to be manually turned on. Monitor Voltmeter if you have one should be 13-14V if charging.
Should be able to run 2-4days off grid on battery especially in summer, the big power consumers will be lights and heater fan. Battery voltage and state.
12.8V 100%, 12.2V 50%. These voltage readings need to be taken with lite loads so best measure with lights and heater fan off.
Try not to take battery below 50% on regular basis, as it will reduce its life considerably.
Switching 12V light bulbs for LED ones will reduce power consumption, as bonus should get better lighting. Cheap from likes of ebay or aliexpress.