You can't buy spring onions in France. The nearest thing they do is "petits oignons" which have small white onions on the end of green stalks. They approximate to spring onions, but if you want the real thing you have to grow it yourself.
There is a little patch of garden between the house and the gite that I have been using for herbs and kitchen supplies. In the picture there is Parsley (self-seeded and hence all over the place), two Thyme plants (a third one that I had elsewhere died over Winter), three Angelica plants and Sorrel. I have also planted spring onions, Coriander and Chervil.
I am starting to wish that I hadn't dedicated the rest of the bed to flowers, but perhaps keeping the veg a bit hidden from guests is a good idea. And here's a free picture of a bag of mixed flower bulbs I bought last Autumn.
Stop press! According to a commenter, you can find them in Asian markets :)