I am replacing the head gasket on my 1.0 Corsa C (Z10XE), which other parts do I need?

Probably cheaper to buy a cheap run around for a couple of hundred quid: Your car won't p it's next MOT, and if you cut corners on the gasket (ie not having the head tested & skimmed), you'll just be throwing your money away. Stick the car 'as is' on Ebay or similar for spares to get a few quid towards a replacement.