LONDON—Talk PR, the fashion and lifestyle public relations firm part-owned by M&C Saatchi, has acquired a majority interest in specialist fashion and lifestyle boutique Store PR, which will merge with Talk's existing fashion team to form a new division, Talk Store.   Talk Store will be headed by Store PR founder Tania Bard, who has led Store PR for seven years, working for clients including Daniel Hersheson, Hershesons Blow Dry Bar, Falke, Charlotte Ronson, Built and Kelly Hoppen. Her team will work alongside Talk PR's fashion team in a new studio space at Talk's headquarters in central London.   According to Talk chief executive Jane Boardman, "Fashion is an increasingly important part of our business with non-fashion clients valuing the connection to fashion's influence. The creation of Talk Store will double the size of our fashion and luxury lifestyle offer and benefit all of our clients' businesses.”   Adds Bard, "This move will ensure that Store's existing clients benefit from the scale and stature of a major agency, while maintaining the senior, hands-on pr service necessary to nurture and build brands effectively.”