Can't connect to localhost:80 (Connection refused)
This means that there is no web server listening on localhost:80. Have you checked with your browser that you can connect to http://localhost:80? Is the web server process running?
My suggestion is to eliminate the web server from the problem, by using file:// URLs instead of http:// URLs. If you want to make your local mirror available to more than one machine, using http as protocol is better, but then you will first need to configure the HTTP server appropriately.
Configuring your HTTP server is not really a Perl problem.
Maybe you can use CPAN::Mini::Webserver as your CPAN web server, but I have never done that.