Teal was brought up in the Kildwick area of Yorkshire. She developed an interest in jazz from an early age, through her father's collection of 78rpm records, becoming "obsessed" with big band singers like Ella Fitzgerald and big bands like Joe Loss. She took music lessons, first on the electronic organ, then more formally on clarinet, before studying music at Wolverhampton University. While at university, Teal found herself without a clarinet for an unexpected examination. Deciding to sing instead, she not only got her "best grades ever", but discovered that she loved singing in public. After graduation, she started a career in advertising, singing in her spare time with amateur and semi-professional bands.
Teal's break came when she was asked to stand in for Stacey Kent at a weekend festival in Llandrindod Wells. This led (after some determined self-promotion, in which she drew upon her advertising skills) to a three-album contract with the jazz label Candid Records. Her popularity soared, with appearances on radio and television bringing her to the attention of a wider public, and in 2004 she released her first album for Sony Jazz in what was the biggest recording deal by any British jazz singer. Don't Talk topped the jazz charts and entered the UK Top 20 UK Albums Chart.
While the majority of her recordings are cover versions of standards, her albums feature original songs and contemporary cover versions, notably a cover of "California Dreaming" by The Mamas & the Papas. This song attracted the attention of BBC Radio presenter Michael Parkinson, garnering significant publicity during her period with Candid Records.
Teal has toured throughout the UK and the world, with her pianist, trio, mini big band, or Hollywood Orchestra. She has worked with the Halle Orchestra, BBC Concert Orchestra, RTE Concert Orchestra, and the John Wilson Orchestra as well as other top big bands. In August 2017, she produced and presented her third concert for The Proms. Swing No End featured two big bands and many special guests. It was broadcast on BBC Radio 2, BBC Radio 3, and televised on BBC Four.
From 2006-2013 Teal presented the BBC Radio 2 show, Big Band Special. In 2009 she started presenting her own show on BBC Radio 2. She has appeared as a presenter on Friday Night is Music Night. Since 2 August 2009, she has presented Sunday Night at 10, took over from Malcolm Laycock.[8] She writes a weekly blog for The Yorkshire Post.
Her final show for BBC Radio 2 was broadcast on Sunday 3 January 2021.[9] From Sunday 24 January 2021 she has joined Jazz FM for a new two-hour swing and big band show.
Teal collaborated with Van Morrison on the single "Carrying a Torch" from his album Duets: Reworking the Catalogue. She was the opening act for Liza Minnelli at Kenwood House and the Royal Festival Hall. She performed at the Glastonbury Festival and the Marlborough Jazz Festival.