<p>If I have no connection to internet, does that mean I can't start <strong>IDLE</strong> (which comes with <strong>python 3.0</strong>)?</p>

IDLE displays a warning message about firewall programs because it connects to the interpreter over the loopback interface, but that interface is always "connected" and doesn't require you to be on the Internet.
If IDLE isn't working for you with Python 3.0, you might consult
Python issue3628
.