Student or Learner
"I'm willing to change in every area that you feel needs work."
Could I use the expression "to need work" in reference to a person to mean they need improvement as in "There are areas in English grammar where she needs work"?
I would find "an area which needs work" more natural, but yours isn't wrong.
There are areas of her English grammar which need work.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.