Is there a washing machine in the villa? If so, then it doesn't matter if some of the clothes get dirty. And if there isn't, then get some of that handwash stuff and you can clean his clothes like that. I've never taken my son abroad, but have been to stay at my parents' several times, and I always pack too much - his clothes take up more room in my bag than mine do! Do you have a beach towel for him? And a high factor suncream of course. For you - just sundresses, underwear, swimsuits and flip flops. Oh, and your make-up, hairbrush etc. Easy! I'm pretty sure you'll be able to buy stuff there if you forget anything.