Dear Client,
I am a former English teacher, proof reader of academic publications and graduate of one of the UK's best universities in History and would be happy to edit the essay for you.
I can complete this project for you in two days or less depending on the length of the essay and what requirements you have for the work, i.e whether you want re-writes or simple grammar and spelling checks.
I look forwards to working with you.
Regards,
Mike Cobb