[6] She has composed for: Psappha, London Sinfonietta, Glyndebourne, Grange Park Opera, Fontana Mix (Italy) Size Zero Opera, The Borealis Saxophone Quartet, RNCM Engage, The Royal Central School of Speech and Drama, The Meon Valley Orchestra, John Miller's Brazmataz, Gillian Blair, Erin Royer and A4 Brass.

[7][8][9] Her work has been performed in venues such as St Martin-in-the-Fields, The Lyric Theatre, The Bridgewater Hall, RADA Studios and St James Piccadilly and her music has been broadcast on BBC Radio 3.

[10] Armstrong was an Royal Philharmonic Society composer in 2021, where she wrote a piece for horn and piano for Wigmore Hall.

She then studied composition at the Royal Northern College of Music under Adam Gorb and Gary Carpenter between 2013 and 2015 where she was awarded the Alan Rawsthorne Prize for Composition in 2015 and was highly commended in the RNCM Gold Medal competition.

Gods of the Game (written with Julian Philips, Aran O'Grady, Abel Esbenshade and Blasio Kavuma) (2022; opera)[13] A Risk of Lobsters (2018; Chamber Opera)[14] Tale of the Tell-Tale Tail (2017; Chamber Opera)[15] Nadja's Song (2015; Chamber Opera)[16] The Library (2014; Chamber Opera) The Alchemical Kitchen (2023; Chorus and Symphony Orchestra) The Gardener (2022; Chorus and Chamber Orchestra) Saxophone Concerto (2023; alto saxophone and chamber orchestra) Life is a Daring Adventure or Nothing (2015; Wind Band) Marine Overture (2012; Wind Band) Dynamic Corpse (2022; flute, Bass Clarinet, piano, electric guitar, violin, viola and cello) The Executioner's Pond (2019; clarinet/ bass clarinet, piano, percussion, violin, cello and double bass) The Whale's Cabaret (2022; horn/piano) The Other Dust (2016; alto saxophone, tenor saxophone and piano) The Singing Fish (2016; alto saxophone and piano) Space Adventure (2015; percussion and loop pedal) SAME SAME BUT DIFFERENT (2016; Saxophone Quartet) Attraction (2015; solo piano) DARTH MAHLER (2015; solo trumpet) Melodrama for Saxophone and Piano  (2014; soprano saxophone and piano) Masculine/Feminine (2015; baritone and piano) Cheese!