The Montpellier region is one of the largest in France in terms of wineries, with over 1,000 estates. But small wineries aren't generally included on organized tours. They have other things to do.
I also suggest considering Montpellier's wine merchants (caviste in French).
Some of them organize tastings. Not only is it a great way to experience wine tasting in a friendly atmosphere, but you'll also be able to taste excellent wines from small producers that you wouldn't have access to on an organized tour.
Some places in Montpellier;
Pousse Pas Mémé dans la Vigne (Don't Push Grandma in the Vineyard) . They speak English
https://maps.app.goo.gl/CFawG17Qensr482J6
La Cave des Arceaux (free tasting on Saturdays)
https://maps.app.goo.gl/myositpzsBkAeCP29
Maybe Elizabeth visits one from time to time.
Avoid the "Nicolas" stores; the vendors could just as easily sell washing machines as wine.
- For the record, "Don't Push Grandma in the Vineyard" is a wine-related adaptation of an old French expression, which meant "don't exaggerate."