It is worth it
Getting your writing corrected professionally is an investment in your academic and professional future. If you can see the wood for the trees but cannot express it effectively in your writing, high-quality correction by independent and knowledgeable experts may add significant value.
What could happen?
Even people with good English skills may struggle with certain written expression, particularly when it comes to academic writing. Errors of punctuation, grammar, or word choice, may creep into your work. Even if such errors are rare, they could negatively affect your final score.
So, instead of trying to scrimp, invest in an effective, high-quality correction of your written English. A professional English proofreading service will pay for itself.