Hi sakthi welcome to javaranch
you will find plenty of mock exams on the net just do a google search , you will also find questions on javaranch ...
one of the best mock exams though is the one in Kathy's book on
SCJP so if you are studying from that book make sure you solve that ( that also happens to one of the best books for SCJP )
You do not have to be working in some company or have any real experience to pass this exam , in fact most of the people who pass SCJP are freshers so dont worry about that
and what are you scared of , just make sure you know all the concepts and also solve as many mock exams as possible and
you should be well prepared for the exam.. fear will only make things more difficult