Hello, I think you can find the mock exam at the end of almost every SCWCD preparation book. If you need, you can try to search and download them. But if you really want to feel confident on the exam, just don't be stingy and buy very good exam simulator - Enthuware JWeb Plus. For only $30 you'll get 8 complete mock exams with profound explanation of every question.
SCJP 6.0(95%), SCWCD 5(94%), SCJD (working on B&S v.2.3.1)