Its not abut the fat content in yogurt , which is of importance to, but more a specific molecule in all dairy that are suspected to mimic human myelin and therefore cause inflammation targeted at the nerves.
The UK home cheese making websites don't seem to have non-dairy cultures, you could use a live soy yoghurt such as Soljade as your starter. You do have to use honey or glucose to feed the culture whatever culture you use as soy milk doesn't have natural sugars such as lactose in cows milk. The Vegetarian and Vegan foundation website has a great dairy free guide - they may know more about cultures. http://www.vegetarian.org.uk/campaigns/ ... -guide.pdf