If US markets are any indication (although probably not?), in a pinch you can look in the "infant foods/formula" area. There are a number of "non-dairy" infant formula substitutes in markets here - even in the ones with very limited "special diet" food sections. You would have to check the labels to see if they meet your criteria.

I can't say what they taste like, but know a number of "former infants" who seemed (as infants) to like - or at least survived - on them. "MulSoy" is one brand (of many) a few acquaintances have used, and is possibly similar to "soymilk"(?) of the normal kinds.

John