My girl was just the same, some things that helped where,
Little and often, if it's only 2 minutes of brushing at a time today then tomorrow will be 3 minutes etc
Take your time, if you hold the Combe gently than you will feel the knots and be able to stop before you pull on the skin.
A table helped and it dose not need to be a groomers table, a kitchen table or an old bedside table, as long as it's safe, I used to stand Bea on a old door mat so she did not slip on the kitchen table by the window, she was then distracted by what was going on outside
Treats are another way to distract and reward for being groomed, I even tried smearing peanut butter or cheese spread onto the table it was a bit messy but worked for a while.
Cockers can be hard work to start with, I like to think of it as the price we pay for having such a cute puppy
Good luck.