before I start I have had a mild anxiety myself, have a sister with moderate anxiety and mother with severe anxiety and depression so I do hear you
BUT...
You need to get a grip and you need to do it NOW. Your anxiety is consuming your life and preventing you from living it and if you continue you will ( not intentionally I know) let your anxiety take over your children's life too.
Your daughter has to go to school, that won't change. If you spend every waking moment between now and September anxious over it she will be going, if you enjoy your time together between now and September she will be going. Being anxious over it is not going to change it or stop it.
You do need help, if as you post is a true reflection of your thought process. It is not a fault to have anxiety, you are not broke, not failing your children not failing yourself but it needs addressing. No your gp can't take her to school but they can offer you the support and guidance to help YOU take her to school comfortably. There are many different things that can be offered which will help you all have a happier future. Health visitors are actually ok, I honestly had no time for them but they have proved a great help to us and yes she came weekly for a while last year as we were struggling emotionally with with sons disability, it did help!
It would be helpful to writ down why you feel anxious if there is a trigger a specific worry etc. are you anxious of people judging you, staring, worrying about the weather , danger, the sheer logistics of the whole operation.
The two buses does sound a pain how fair is it can you not walk some at all or possibly help to transport costs.
I know all that sounds a bit harsh but I desperately don't want you to miss out on being with your children and enjoying life together through your anxiety. My own mother missed so much and still does as its too much of an issue, she is getting. Better now very slowly but it's a lot of years lost. Don't let it happen to you Hun please go and get the support u need xxxxxx