How can I stop my pastry breaking up?

Cooken is brilliant, stick to your recipe measurements they are right. Use cooken instead but it has to be really cold. When your rubbbing your flour and fat together dont be too particular a few lumps and uneveness is fine. Then take the bowl o the sink and start the cold tap running. add in a few tablespoons of cold water and mix with the spoon to bind you may need more depending on your flour. keep mixing and adding until the dough is not sticky but has all muixed together and come away from the sides of the bowlto make your dough. flour your surface and give it a very quick knead. wrapin grease proof paper as clingflim will make it sweat, and pop it in the freezer for 20 minuets this hards the fat back up giving you a short crust but also when you roll it out because the fat it warming it wont crack. good luck