By way of an update I fitted the microphone, and the audio patch lead and the system works fine now.
Like Jo, I couldn't find the 'empty' connector for the microphone patch lead but seems this is not needed. Mine is a 2010 Focus with a build date of 22/1/2010.
Thanks for your help Gaz
I am having problems locating where the Audio patch lead goes, could you please let me know where yours was. Mine is 2009 Focus with a build date of 25/06/09. Thanks