Revise your book as your conscience dictates. Do not change your unique personal writing style. All editing and changes for your book-manuscript is solely up to you. Make certain your manuscript stops at about 100,000 words (optimum amount for getting published - few publishers will publish manuscripts with more than 150,000 words).
I invested in Microsoft Word that catches the majority of grammar errors and spelling mistakes. It saved me a bundle in editing fees. My grammar plus spelling error-free manuscript titled "Just Alex" impressed by publisher into publishing it. Most publishing houses have their own editors who edit manuscripts for them. Find out which publishers you want to have for a publisher and check to see if they have on-staff Editors or have an editing service.
Highly recommend using Microsoft Word to polish your manuscript before submitting it to an Editor or publisher. This way the publisher is impressed by your English skills. An Editor's fees are usually less if there is zero grammar or spelling mistakes. An Editor can give you superior editing tips regarding your manuscript’s content if it is error free.
Another thing you can do is ask a friend to read it and see if they notice any mistakes or have suggestions. These are very helpful for most will notice sentences that do not run smoothly. Tell them if they read it, they get a free dinner or lunch. My friends who read for me usually accept this as a reading fee. This assists with receiving a reader's feedback.
Good luck with your book length manuscript; may it become published soon. Good hunting for the right publisher for you.