Have you tried soy products in place of dairy? I've taken most dairy products out of my DDs diet as it was giving her severe constipation and I found the more she held it all in, the worse her behaviour got. Anyway, she luckily loves soy milk...I get one with extra calcium and high fibre in it. I recently tried the soy yoghurt on her and she loved it. I tried it myself and it actually tastes like custard - yum . Cheese; you can buy vegetarian cheese which is actually quite nice as well.

You can buy breads without preservatives if that's an issue. Bakers Delight also maintain that they sell all their products without preservatives.