I would take the following:-
Tent, mallet, spare pegs, something to sleep on (either camping mats, airmays, airbeds etc), sleeping bags or duvets, pillows if you like.
Folding table and chairs if you have them.
Cool box, couple of large plastic storage boxes, cutlery, plates, bowls, cups, glasses, sharp knives/chopping board if you are going to cook for yourselves, food items (at least basic tea/coffee/milk/juice/wine/bread/butter etc).
Washing up bowl, liquid and cloth/sponge/scourer.
If you want to have a barbecue and already have one, take that. Camping stove (there are loads of types, can't really advise you), matches. Loo roll, kitchen roll, foil, torches.
Clothes, including waterproofs, towels, wash things.
Have probably forgotten loads of stuff, but at least that's a basic list.