Should you try to write a novel if you are hopeless with grammar.

Firstly I would like thank all of those of you who have commented on some of my previous questions. (thank you)

This questions I ask is I suppose a bit of a silly question. But I have had a poor education as a child, and was neglected because I was not as sharp as the others in my class. But I am trying to resolve this issue. I am taking a writing course with the OU this year. Back to the question I have though, I have a yearning to write a book and can't stop coming up with ideas for stories. Yet I know my grammar and punctuation is well below the standard it should be. But I also believe in dreams and my dream is to have a book published before I die. I am not going to question my luck by saying that I think I have time on my side, because the opposite to that is you never know what is around the corner. As I am fully aware of as I was involved in a head on collision car accident last November. So I do think that I am been given the chance to write my book. Another reason I ask this question is that I am aware of other authors that also have not had the literary skills. Yet have gone on to produce a grate piece writing and that in turn has gone on to become a blockbuster film. The author in mind is Andrea Dumbar, and although her work started out as a play to start with it eventually went on to become a book. I suppose the point I'm trying to ask is could I learn as much from reading different styles of writing. Than actually taking some written exam just so I have proof that I've Studied. I think I have the structure to write a good story and I know that research is the key getting things factual. and if your story is believable then the reader will let you take them on the journey you wish to take them. I hope some of this makes sense to you when you read it and I hope you can give me some Ideas and advice on what would you do in my shoes. ( Thank You)