I am a native English speaker. Although I now live in South Africa, I started school in England, and both my parents were English.
I love to read, and I'm intrigued to know more about your story. The first thing I would need to know is something about your target audience. For instance, if it's a children's story, the language needs to be appropriate for the age group. Depending on the length of the story, we may need to set some milestone deliverables, but that will come should you decide to take this further. I have allocated 5 days in my bid. It shouldn't take that long unless it's something like War and Peace, but I like to leave enough time to go over everything twice.
I would love to help you with this project.