Sadler was born in Ascot, Berkshire, and grew up in High Wycombe, Buckinghamshire. As a young girl she enrolled at the Jackie Palmer Stage School in High Wycombe, before joining the Sylvia Young Theatre School in London. She was spotted as a future talent at the age of six by Dustin Hoffman, who had seen her in a play and asked to meet her. Before joining the cast of Holby City, her best-known role had been as the character Judi Jeffreys in the children's television seriesGrange Hill from 1997 to 1999. Her Grange Hill character was killed after slipping and falling out of a burning building, tragically paralleling her real-life death four years later. Laura also played the part of Skirty Marm in a BBC1 children's comedy, Belfry Witches. Skirty Marm and her friend Old Noshie were teenage witches banished to Earth from Witch Island, settling in a sleepy village where they caused mischief. In 1996 she starred in the feature filmIntimate Relations alongside Julie Walters, where she played a Lolita-like girl with a crush on her mother's adulterous lover. She joined the cast of Holby City, a spin-off series from the long-running BBC medical drama series Casualty, in the show's third series, playing the nurse Sandy Harper up until her death.
Death
In the early hours of 15 June 2003, Sadler fell 40 feet from the balcony of the Holland Park flat of her boyfriend and Holby City colleague George Calil. She had consumed a large quantity of alcohol and was later found to have had traces of diazepam and cocaine derivatives in her blood. Sadler suffered severe head injuries and never regained consciousness. Her family decided to take her off life support on 18 June 2003 and she died at Charing Cross Hospitala day later. Sadler's funeral was held in her home town of High Wycombe, and she was cremated at Chilterns Crematorium. Calil was questioned by police, but later released on bail and never charged. Sadler's death was ruled as an accident. Sadler's character continued to appear in pre-recorded episodes of Holby City for a while after her death. Her mother aided the show's writers in conceiving an exit storyline for Sadler's character Sandy Harper. In the episode, which was broadcast in September 2003, Sandy was revealed to have won the lottery and subsequently emigrated to Australia.
