Julie Etchingham investigates how smaller political parties could hold the balance of power this election and finds out what drives the politicians leading them. She discusses power and childhood memories with the SNP's Nicola Sturgeon and her husband over breakfast, Plaid Cymru leader Leanne Wood takes Julie back to her old school to meet the teacher who inspired her politics, and the Green Party's Natalie Bennett talks about her infamous 'brain fade' moment over a coffee.