Complex sentence: On 3 August 2011, it was announced that she was to present ITV's "London Tonight", providing maternity leave cover for Nina Hossain, and relief presenter of the main "ITV News" programmes from mid-November until Spring 2012.
Split into simpler sentences: On 3 August 2011, it was announced that she was to present ITV's "London Tonight" programme, providing maternity leave cover for Nina Hossain. During this time she was also a relief presenter of the national "ITV News" programmes from mid-November 2011 until Spring 2012.