Andrew - all the electrical boxes on the site are locked. The staff come to connect you up and as we did not have the continental fitting they connected one of theirs to the main box and then ours was connected to it. I asked about polarity and they said all was OK. For the two weeks we were there we did not have any trouble with the electrics. When you leave they will disconnect you and take their convertor back to reception with them. The majority of the staff speak good English, only ones who were not English speaking were the shop and take-away staff. Be careful - all newspapers except the Telegraph are 24 hours old and cost 3 euros each, including the Telegraph.
I would suggest that you contact them well in advance of the holiday to ask if you can have a pitch near the beach. We did this and had a pitch 10 feet from the beach - it was brilliant.