Hello, I am finishing my one year research degree in a few months. I have almost finished my work and I aim at a distinction grade.
After consulting my supervisor, he suggested that the content and structure is fine, however there are some -not mistakes- let's say incorrect phrases or use of language or unusual expressions due to the fact that English is not my native language. I can correct any grammar or syntactic mistakes by my own, however I am not sure if I can write in a fluent english academic style of expression (for example in my native language scientific speech is based on long sentences, in which I am used, or we use many commas, however it 's not the proper english way). So, my supervisor advised me to use editor/proofreader services, in order to secure my grade. Moreover, I would need some assistance in formatting my essay, especially concwrning citations style. My supervisor also suggested that I could pass my essay by turnitin before submitting, in order to check for any citation mistakes leading to not intended plagiarism.
I would like, therefore, to ask if you could suggest any serious and trusted proofreader/editor in U.K. I do not trust internet based editors.

I hope that you will not misunderstand my question.
Thank you in advance.

I assume, you'd better to contact with a teacher from the college which specializes in teaching english language and negotiate with the specialist.