So sorry to hear about your daughter but great that she has her diagnosis as that is often the most traumatic phase. Both my children are coeliac, one diagnosed age 3 and the other age 5. Now your daughter is on the correct diet things will start to improve. The important thing is to be really strict at this recovery stage eg separate butter containers, dedicated slot for her bread in the toaster, avoid contamination wherever possible. The main problem for us was children's parties and playdates where they had to bring their own tea and cake. Eating out was difficult too as almost all kiddy food seems to contain gluten! It's a lot better now though with Pizza Express and other restaurants offering gluten free food. Everyone has been very good though at accommodating my children's food requirements and once I explained that it isn't like a nut allergy ie if they eat gluten by mistake it won't kill them, they'll just feel sick or get diarrhoea, they felt comfortable with it.
Don't worry too much about what you read. Your daughter has been diagnosed early and is highly unlikely to suffer from any complications. I expect that you will have at least an online/phone check up in June (I would check with the hospital to see if this is the way they want to go). Not ideal but most importantly they'll want to check her weight and height to see if she is responding well to her new diet. You can do that yourself too and plot the results on her growth charts which hopefully will reassure you.
I'd be happy to meet up for a socially distanced chat any time soon. I live in Balham.