You should get documentation for the court to backup your claim you were ill. Your best option would be a statement from your doctor signed under penalty of perjury. You can get a declaration form that the doctor can complete. Get your response filed right away, even though it is late the judge can still consider it especially if he finds you had a good reason for being late.
The judge has the ability to order you to pay his fees given the facts you've described. However, judges will also take into consideration other factors like the reasonableness of the filings, prevailing party and need and ability to pay.
My nest advice is to cooperate with CWS and follow your case plan. If you begin work on your case plan in the early stages you show the judge that you are committed to getting your baby back. Even if you do not agree that you need the services, by the time you get to trial you could have completed a significant portion of your case plkan and established yourself as a parent whose primary focus and concern is the best interest of their child.
You can seek the assistance of the Department of Child Support Services to enforce your order. They can obtain a Wage Assignment against his unemployment benefits. The children may also be eligible for MediCal. DCSS can also obtain an order requiring that he seek work, intercept his tax returns, suspend his license and ability to register his car . . . and his unpaid support will begin to accrue interest.