Preparing to get the bus to school

In all honesty, I am nervous. My daughter will need to get the bus to and from school next year in order to go to school which is what she wants. 

I really don't know how to help her with this transition. She loves getting the bus but she is always with a family member. She did have to get the bus to a local mainstream school and that caused hideous meltdowns and anxiety mainly because of the school kids on them.

I am worried that she will not cope if there are school kids on them which is likely. I can't walk her to the bus stop because I need to take both my other children to school at the same time. 

I do know she will be fine walking to the bus stop from home and getting off the bus after school. I feel she will massively struggle with walking to school and walking away from school. There is a McDonalds round the corner and many shops which I know she will be tempted to go to. I also fear how she would react if the bus was late in the morning to get to school and what would happen if the bus got stuck in traffic. Its a 40 minute journey without traffic. Also what will happen if she refuses to leave school and go home or if she has a bad day and is dysregulated. I am not able to come and collect her because I will need to get the kids from school and my husband will be working but if one of us does, it will take an hour to get to school. I have said that if we do need to get her then she will not go back, unless it's because of the bus or something out of our and hers control.

How can I help with this and also she will be extremely anxious already because of the other changes and she has not done a full school day for the whole school year so who knows how she'll cope. She might surprise us yet but we always prepare for the worst.