depends where you buy parts, if you replace all belt pulleys and water pump and if you have the head skimmed.
you could prob do it for £30 with an ebay head gasket kit which inc bolts if you dont replace belt, pulley, tensioner and pump and dont have the head skimmed.
but i would recommend that the least you get is head gasket, head bolts, belt kit (inc tensioner and idler) cam seals and skim the head.
it would make sense to do the water pump at the same time aswell and replace inlet and ex manifold gaskets.
you will also need to replace the oil and coolant.