Now that I've given up the glyphosate as a weapon against the ground elder, I need some alternatives. Bristol City Council are trying vinegar, so I'll keep an eye on that trial, and have a go myself. Naturally, it won't be as effective as glyph, (duh!) but the idea is to keep weeds in check, not necessarily eradicate them. And it depends on how often you spray, too.
Getting vinegar is not a problem. A few years ago, I got kilos of strawberries from the fruit and veg shop. Dad used to go there to get whatever they were throwing out, for his chickens. I made several gallons of strawberry wine, but a vinegar fly must have gotten to it because I ended up with several gallons on strawberry vinegar. So any fruit will do, just make the wine and don't worry if some of it goes to vinegar, it will find a job with the weeds.