Hello Newbie
With the fitting of a 12Vdc to 230Vac inverter you could run a limited number of 230V appliances without a mains hook up.
The usual problem is that 230V appliances tend to use a lot or power and the 12V batteries in caravans/motorhomes are not a bottomless pit of energy
For example trying to run 1kW fire requires a 1000W at 230V that would require a battery to be able to supply an inverter with at least 85A. most caravan batteries would not last an hour before being completely flattened and possibly damaged by drawing so much current, and you would need a big inverter to handle the power.
They do exists but, but a good quality one with a pure sine wave output would be several hundred pounds.
In reality you have to compromise a little, The big electrical power users are usually heaters, for which there are usually gas powered alternatives already fitted, Smaller items like TV etc, there are some that can be plug directly to the 12V dc circuits.
Using a site with an Electric Hook Up is a usually a much cheaper option, or find the delights of living without relying on instant 230V power at the flick of a switch - It can be fun!