Your first hurdle is how to get your work noticed. The more your manuscript is cleaned and polished, the more it can sparkle in a publisher's in-tray. Wouldn't you be more inclined to read a manuscript that flowed rather than stuttered along? Copy editing will present your work at its scintillating best and put you one step ahead of the competition. You stand a better chance of gaining attention if you submit a readable script − it will reflect your commitment and pride in your work.
If you decide to self-publish, your work most definitely needs to be copy edited and proofread before you invest your money in producing bound copies. Remember, when your script is with a typesetter it can be costly to correct errors and you should not even contemplate making changes once your book begins printing.
Self-publishing needs to be weighed very carefully as you will be financing the entire production process. You will also need to market and sell your book, supply copies to booksellers and other outlets and collect income from sales. Of course, you may decide to print just a small quantity for distribution to friends and family. Whichever route you follow, it needs to be from a firm base of a well written and scrupulously edited manuscript.