Hi I'm trying to wire power from my house to my flat they told me that I must use 10mm cable . I would just like to know what amp size trip switch I must use on the main bord that supply's power to the flat. There will be 5 lights 4 plugs a oven and geyser running from the panel in the flat self.

You may want to mention your location since most here are in North America and you obviously are not.
Sorry, I have no clue about European wiring practices and codes.