I have no idea about any good teacher specifically for CSS in Peshawar. However, a 5 weeks special English course is going to start next month in University of Peshawar which is specially set up for English Essay and English composition paper of CSS and PMS.
You may visit the following link for detailed information.
http://www.upesh.edu.pk/admissions/a...-notices/?q=34

Remember: Last date of registration is 30th August 2013.