I am having a real battle every school morning with dd1(6).
She refuses to get dressed for school and the whole situation always ends up with me shouting at her and both of us feeling really miserable when we actually get out of the front door.
I asked her this morning to ready for school and she point blank shouted back at me "NO!"
How are you supposed to respond to that.

I have tried the usual things:
If you don't get dressed you will not be going to rainbows/swimming/gran's for a sleepover etc etc etc.
If you don't get dressed you will got to school in your nightclothes! 
...there will be no pocket money/sweets etc.
How do you handle yours?