OK - I'm back! Lisa has given a really good overview.
Lisa - I'm jealous that your paed has allowed you to "challenge" Archie. Our allergist is *so* super-conservative and we're not allowed to let Amelia try anything at all!

I agree with Lisa - Amelia has never been effected by the dairy that I eat flowing through to the breastmilk. Once she was diagnosed I was told I'd have to cut dairy out of my diet. Since I'm a Coeliac and already live on a pretty restricted diet I challenged the allergist and pointed out that Amelia didn't have a reaction in the first 6 months of BFing so she let me continue to have dairy myself.
Amelia was first given S26 formula at 5.5 months ol. She didn't like it (fortunately!) and spat the whole lot out. Wherever it touched her skin, she broke out into hives. A trip to emergency and subsequent allergy testing later, she was diagnosed with severe dairy and egg allergies and a milder soy allergy.
We were given an Epi-pen in case Amelia came into contact with dairy (even on her skin) as she was considered to be severe enough that she might go into anaphylactic shock. We were also given a prescription of Neocate formula which is dairy and soy free. Initially we just used this in place of milk for cooking/cereal etc but she now has bottles of Neocate while I'm at work. Otherwise, we fully BF (still at 16 months).
When we started solids, we were given a list of foods to start with (fruit and veg) in a specific order of least allergenic which we started on first. We had to introduce everything extra-slowly and watch for reactions (esp. to citrus, banana, wheat, meat protein etc). I also had to carefully read all ingredients lists for signs of dairy, egg and soy (eg: casein and whey are dairy products) - luckily for me I was used to reading ingredients for myself (being Coeliac!).
My main worry is that now Amelia is older, she is running around with other kids and potentially picking up other's food or sharing something she isn't able to even touch, let alone eat.

This really stresses me out and I'm not looking forward to having to put her into childcare later this year.

We are obviously still completely avoiding dairy, egg and soy. We have had Amelia tested again just before Xmas and her allergies are still well and truly there, so we will have to wait and see if she grows out of it in time. I was told that 60% of kids grow out of it by age 3.
Hope that helps and happy to answer any questions you may have!