Hooray for the Internet! thanks to the lovely helpful people in the cycling newsgroups, I have found out that I can prob get my wheel going again without having to do scarey sprocket removal stuff, because app. you don't have to have the cage thingy and can just put bearings 'n' grease in. I am going to take wheel to bike shop this afternoon, and hopefully my bike maint teacher will be there too, and will get it sorted and bike back on road again by this evening.