Your university probably has a web interface to registering a mac address. You can use a public terminal to do this. You can also use a public terminal to download GNU macchanger and give your current machine the same mac address.
If you don't already have the software, like wpa_supplicant, to access the eduroam, you'll need to use the ethernet, generally.
Once you have ethernet access, download what you need to continue. This is what I would do, anyway.