quidnunc
Welcome to the forum, you might want to have a look at the following FAQ which explains where everything is
Welcome to Benefits and Work Are you requesting a Mandatory Reconsideration or an appeal?
The assessment report is not sent as standard it has to be requested from the DWP office dealing with your claim.
You have two choices, send in the request on time but say that you will be providing additional information when you have received the report, you will be given four weeks to provide the information but this includes postage.
Or, you can make a Late request citing the delay in receiving the report as Good Cause for it being delayed.
Gordon