Hi Stuart and welcome to the forum. I'm sorry to hear about your lovely daughter and I understand how you must be feeling right now.
Education is the key and if you have not done so all ready, then ask your diabetic care team about a DAFNE course. This will teach you how to match insulin to carbohydrate in the food your daughter eats, thereby keeping her blood more stable and avoiding the swings between high and low.
I would also recommend the following book Type 1 Diabetes in Children Adolescents [Paperback]
Ragnar Hanas (Author) . It has lots of useful information and although it does go quite in depth it does cover everything in a clear and concise manner.
At the moment, it must seem like you have a mountain to climb, but things do get easier overtime. I'm not saying it eventually will be all plain sailing, but things will get back to normal and managing your daughters diabetes will become a way of life.
This site has lots of other parents who are always on hand to answer questions, offer support and even a offer a shoulder to cry on. I came here when my kids were diagnosed 3 years ago and have found the help and support invaluable and I hope that it can help you as much as it has me.