Complex sentence: After a period working in New York, she returned to London in 1975 to help launch another new magazine, "Street Life", later joining "Time Out" before leaving in 1980 to help found the more politically radical "City Limits".
Split into simpler sentences: After a period working in New York, she returned to London in 1975 to help launch another new magazine, "Street Life", later joining "Time Out". In 1980 she left "Time Out" to help found the more politically radical "City Limits".