Clio’s cylinder head gasket?

Hello Sportsfriends, my Clio, 1.2 Rn, Bj 92, constantly loses water, sometimes there is white water vapor in the exhaust gas (even with warm engine), sometimes starts off badly or mostly has not the full power. Do you think that could be the Zyl. head gasket? Would you like to replace it yourself, had changed half the car on my golf, but I have never disassembled the engine. What do you think is this as a talented, advanced hobbyist with numerous tools ( And with the book “now I help myself” to create? What do I have to pay attention to? Which seals do I need and where do I get them as cheaply as possible? Who can share his experiences with me in his exchange of poetry, and what problems do I have to pay attention to? Just, don’t be afraid of writing, I am happy about every helpful word and thank you very much.