Nicholls was born in Worcester in 1977.[1] She studied Equine Science at Hartpury College and works as a teaching assistant at Winchcombe Abbey School.[2][3]
Nicholls was involved in a serious car accident which left her with heart complications.[2] From 2001 she had a series of strokes, while a stroke in 2008 left her unable to use her left arm and leg.[2][4] In April 2009 doctors discovered a hole in her heart for which she underwent corrective surgery.[2]
Nicholls first wheelchair race was at Stoke Gifford at an open event in 2010.[1] In 2011, she was classified as a T34 athlete and that summer attended multiple meets across Britain as well as events in Switzerland and Netherlands competing in the 100m, 200m, 400m and 800m races.[1]
By early 2012 Nicholls had posted a sub-21 second 100m sprint and qualified for the Summer Paralympics in London, as part of the Great Britain team, in both the 100m and 200m events.[1] In the 100m she was drawn in the first heat but her time of 22.41 saw her fail to progress to the final.[1] In the 200m heats she finished fourth and qualified for the final.[1] Nicholls finished seventh with a time of 40.00.[1]
In 2014 Nicholls represented Britain in the IPC Athletics European Championships in Swansea. There she won her first major international medals, with a bronze in the T34 100m, and a silver in her favoured 800m event.[1] In the 800m Nicholls finished just a second behind teammate Hannah Cockroft with a time of 2:16.68.[6]
In 2019, Nicholls set a new world record, handcycling from Land's End to John O'Groats in under seven days. In 2021, she undertook a 75-day, 4,800-mile handcycle journey around the coast of the United Kingdom, starting and finishing in her hometown of Tewkesbury, and raising £1,590 for Ovarian Cancer Action.[5]