Work capacity assessment

To ask for your Work Capability Assessment (WCA) report, you'll typically need to contact the DWP office handling your claim. If you're claiming UC, you can request the report through your online journal. If you've already received a decision, you can also request the report from the DWP office by phone. 

"how? and was it useful to read the report ?"

It depends on one's own reasons for wanting to read it.