Head gaskets are quite expensive to get done at a garage, when i got a quote it was £300, so me and a friend did it. the parts are pretty cheap, you'll need the head gasket set & bolts (u can get em off ebay for £28), cam belt and tensioner (if you've got the head off, may aswell replace these there only about £15), new engine oil (about a tenner), and new antifreeze (£5), as well as a tube of gasket sealent (£5) so you're only lookign at about £50 for the parts, if you've got anyone thats able to do it with you. its not that hard, more time consuming than anything.
edit: Forgot to add you'll need to check the head when it comes off, might need it skimming at a machine shop, probably cost about £20.