My son worked in Argeles as a courier for Canvas Holidays - but I personally would say that the beach is not the best for such young children. There's a steep shelf, almost a step, where the sea and sand meet, so it's difficult for little ones to get in and out! There are other sites where the beach is flatter, and which are much safer for younger children - but as my children are grown-up now I'll let someone else give some suggestions.