How to access iTunes library from iOS device via HomeSharing when Mac is sleeping

Might be a long shot, but have you tried disabling IPv6 on your Win 7 pc?

If you have a large library, it will take a while for it to get the contents over Home Sharing, particularly depending on the wireless connection speed. Home Sharing is the expected way to do what you're trying to accomplish, simply let it finish doing the initial library transfer. If it's not giving an error, saying it is unable to connect or activate Home Sharing, then it is working.

The other options would be to sync the music to the iPad (wired or wirelessly), use iTunes Match to get the content directly (it, too will have to load the library data like Home Sharing does), or use a third-party method of sharing content from the computer to the iPad (like Plex).

It's also possible you're encountering network errors of some sort if you are receiving an error message of any kind (or if it succeeds but just takes a crazy long amount of time). It may help to review http://support.apple.com/kb/TS2972 or http://support.apple.com/kb/TS1629, depending on your network setup. Home Sharing requires UDP port 5353 to be open, which normally should not be an issue inside your network unless you have a very unusual setup.