If it was me I would be purchasing a genuine Vauxhall clutch kit, and a new slave cylinder as well.
Never change the clutch without changing the slave cylinder as well.
I'd have a GM clutch over that fast road one too. How many miles has your clutch done?
Part numbers for your car (using your chassis no)
93185882 - Kit, clutch disc, pressure plate and slave cylinder. This should be everything you need (including the slave cylinder) but PLEASE CHECK with Vauxhall BEFORE ordering to confirm I am correct!