Not soup exactly but some of the Easy Bean and Stewed! pots are free or low syn. Also the Innocent pots have a couple that are not too bad. I've highlighted the ones that are free or less than 5 syns. Lots of supermarkets have started doing their own but Ive not tried any yet.
Easy Bean:
Moroccan Tagine, chilled, 320g pot Free
New Mexican Chilli, chilled, 320g pot Free
Indian Sambar, chilled, 320g pot 4
Spanish Puchero, chilled, 320g pot 6½
African Palava, chilled, 320g pot 10
Stewed!
Chickpea, Sweet Potato & Feta Stew, chilled, 325g pot Free
Hungarian Goulash, chilled, 325g pot 3
Chorizo, Chickpea & Pork Stew, chilled, 325g pot 7½
Chorizo, Chickpea & Pork Stew, chilled, 325g pot 7½
Thai Green Chicken Stew, chilled, 325g pot 8½
Veg Pot, Roasted Aubergine Moussaka, chilled, 380g pot 2½
Veg Pot, Moroccan Roasted Vegetable Tagine with Couscous, chilled, 380g pot 4½
Veg Pot, Sweet Potato Chilli with Chargrilled Peppers & Paprika, chilled, 400g pot 4½
Veg Pot, Italian Mushroom Risotto, chilled, 380g pot 5½
Veg Pot, Piri Piri with Patatas Bravas, chilled, 380g pot 5½
Veg Pot, Indian Vegetable Masala, chilled, 380g pot 6½
Veg Pot, Mexican Sweet Potato Chilli, chilled, 390g pot 6½
Veg Pot, Peas, Broccoli & Mint with Creme Fraiche & Brown Rice, chilled, 400g pot 6½
Veg Pot, Thai Coconut Curry with Soya Beans, Pak Choi & Wild Rice, chilled, 390g pot 8
Veg Pot, Indian Daal Curry with Spicy Cauliflower, Fresh Spinach & Rice, chilled, 380g pot 9½