I live in France and I can't drink milk and I find soy and almond milk without problems.

I will mention that I usually find it too sweet but that might not be a problem for your child. You may want to buy "nature", which doesn't mean "natural" but "unsweetened" (think: "natural state") and add your own sweetener.

Organic stores have the best selection. Remember that organic is "bio" in French (biologique). In supermarkets, you'll find it where the UHT milk is kept. The French use a lot of UHT milk and the soy (and others) are usually there. If not, most bigger stores have a "bio" section and you'll find milk alternatives on those shelves, usually towards the bottom.

Soy is "soja" and almond is "amande" so those are easy to recognize. Goat's milk is "chevre" and usually has a picture on it. Sheep's milk is "Brebie" (which is "ewe" actually) and it's harder to find. Rice is "riz" and oats are "avoine" and those milks are also sold here. Read the ingredients to be sure there is no cow's milk added. That used to be a problem when I first moved here but it's found less often now. Thank goodness!

Not sure if you're into organic or not. I'm somewhat but not completely converted but I find the organic better quality. My favorite brand is "Bio Village" but "Soja Sun" is more common and I drink it.

You can also find a pretty generous selection of soy yogurts and other products. They're starting to mark things "Non OGM" or "sans OGM" meaning the soy (or whatever) is not genetically modified.

Be sure to mention it in restaurants and you'll find that they're usually very accommodating. You may want to remind them of butter (they're thinking "no milk") and other products. I find that I have an easier time in France than many other places because creamy and or cheesy things are obvious whereas I had trouble in England because they added a little bit of cream, milk or butter to everything.

Be sure to bring any medications your child will need if he accidentally eats something.