Although you have no fridge, what about taking a cooler back with some cooler blocks in. That way you could take things like, bacon, sausages (WW Premium Pork Sausages are half a Syn each), eggs. Baked beans and/or tins of chopped tomatoes. Take some onion, mushrooms and tomatoes with you and grill those - there you have the perfect Slimming World fry up. Don't forget the FryLight!
Pasta'n'Sauce, Fat Free SuperNoodles, MugShots - they all just require boiling water to be made, and a lot of them are free! You could easily make your own pasta and sauce though which would also be free and super yummy! Just boil some pasta. Whilst thats boiling fry off some peppers, onion and mushrooms in frylight. Add 1 tin of chopped tomatoes and garlic/chilli to taste. Serve over the cooked pasta. Voi la, as simple as that!