It depends whether it's fiction or non-fiction.
If it's fiction, all that really matters is how good your writing is. Taking a degree in creative writing or English literature might help to make your writing better, but it won't (by itself) make your book any more likely to get published.
If it's non-fiction, you have to be able to demonstrate what's known as "platform". This is approximately "why would someone read a book about this subject by you, rather than anyone else?" For example, if you want to write a book about the history of France in the 19th Century, it would help if you were already acknowledged as an expert in that subject - say, by being a professor of history at a prestigious university, specialising in that country and that period.
