How much recording time at 1080p30 on a 32GB card on a GoPro Hero (1)?
Have you try to go to the product web site and check?
http://gopro.com/support/articles/recording-time-in-each-video-setting

I know it is about Hero2, but i think the values will not change much. Be aware fully charged battery will power the camera for no more than 3 hours