Im not sure about ready made soups being syn free. I always make my own but I know there are a few that you can use as HEXB's. Your book should tell you more - red day - 208g serving of baxters healthy choice soup Italian bean and pasta, veg soup, carrot and butter bean, spicy parsnip.
300g baxters favourites scotch veg soup with lamb
320g serving of baxters healthy choice soup chicken and veg, lentil and veg,minestrone with wholemeal pasta,veg soup, tomatoe and butterbean.
green day - same
soups for syns -
the lowest i can see in my book - low cal chicken, mushroom, tomatoe veg per 100g = 1.5 syns
there are plenty others going higher in syns