There are so many good links/books from where you can find enough information to prepare to
SCJP.
Books:
Java 2 Exam Cram, Second Edition -by Bill Brogden,
Thinking in Java
A Programmer's Guide to Java Certification - Khalid Azim Mughal, Rolf Rasmussen
For Mock Exams ,visit this site
http://www.levteck.com/ You will get bunch of mock exams.
I hope this will help you..