Hi Allyson
There are several answers to your question.
Firstly you need to confirm the polarity 0f the 230v coming into your van. This is done easily with a polarity tester that are available from most caravan shops and is a simple device that you plug in to a mains socket in your van once you have hooked up to the electric hook up(EHU) Once plugged in a series of lights will illuminate confirming the polarity from the EHU is correct or not(follow this link www.towsure.com/product/545-mains_polarity_tester_plug)
If all is O.K you need not take any action. Get out a beer and chill.
If the plug says the polarity is reversed you need to change it back again which is done by reversing the polarity:
1/ Buy 2 x continental adaptors. These have two pins and a small socket for the earth(see link www.wilmond.co.uk/acatalog/mains_connection.)
One of these you will have to reverse the polarity by reversing the brown(live) and Blue(Nutral) at the Blue end of the lead.(If you are not sure how to do this safely get a competent person to do this for you) This will correct the polarity coming into the van, make sure you clearly label which is normal polarity and which is reversed.
You may not need the continental adaptors as many sites in France and Europe are changing over to the system used here, but again the polarity may be reversed in which case you will need another polarity changer.
2/ In this case this will be made up of two blue connectors as used on your site lead(One male and one female)but you will require a short piece of orange site lead and one end has to be wired as normal Brown live, Blue nutral and Green/yellow earth. The other end that you have will have to have the neutral and live reversed (Brown to nutral/blue to live). Again if you can't do it get a competent person to do it for you. (See wilmond site for the connectors)
These options will give you every variable to deal with reversed polaraty abroad.
If you find that the tester plug says the EHU has no earth speak to the site and tell them you need a EHU with an earth. This has only happened to me once in 30 years of going overseas, but reversed polarity is quite common as both the nutral and live are fused in Europe.
NEVER change the location of the earth wire.
Hope this helps
Rob