We sort of do Greyduster, and it's a great idea. I'm not familiar with the state system, but I'm sure that under the National Curriculum in England, learning a foreign language is compulsory for pupils in Key Stage 2.
However, therein lies several problems. From observing my DGC, language lessons aren't regularly tacked onto the working week, but just delivered when the class teacher has a bit of spare time. And there's another problem. The class teacher is by no means a specialist in languages, and therefore shouldn't be expected to teach a foreign language. So, basically she teaches the children several mistakes which will have to be unlearned later. The children do appear to enjoy singing some French songs occasionally.