I would put a selection of breakfast food on the table, tell her it's breakfast time then sit down and eat some yourself, not paying any attention to if she joins or not. I think 30 mins tops is long enough for breakfast. Give her a warning eg 5 more mins until breakfast time over and then put it away.
On the way to school is there anything she can eat eg cheese, fruit, nuts and raisins that is more of a snack time food that she will eat. Maybe what she has for snack at 11am. Do they have snack at school?
I think try to make a less of an issue as such for a few weeks, at least a month while she settles in. She won't starve.
Then if things are still not going well I would perhaps sit down and explain why it's important to have BF, back up with books. Then have a menu she can chose from eg scrambled eggs, cereal toast, smoothie anything she likes that she chooses before going to bed so you can have it ready in the morning. You could also use a sticker chart at this time if she eats the BF, or what I've done in the past is have hot chocolate for after eating.