Catherine began her acting career as an “extra” in the 1996 comedy short 'Mirror, Mirror...' In 2000, she appeared as ‘Sue’ in the British sitcom 'Time Gentlemen Please' and had a brief role (as ‘Colette’) in the 'ITV' drama 'London's Burning.' Around the same time, Catherine began her stint in the radio circuit.
Catherine performed as ‘Daisy’ in the comedy 'Think the Unthinkable' and then appeared in the themed audience sketch show 'Concrete Cow,' both aired on 'BBC Radio 4.' Catherine also co-wrote the script of the latter and the 'BBC Radio 4' show 'Afternoon Play: Cats and Monkeys.' Her other radio credits as a performer include shows such as 'Safety Catch,' 'Listen Against,' 'Miranda Hart's Joke Shop,' 'Brian Gulliver's Travels,' 'Giles Wemmbley-Hogg Goes Off,' 'The Simon Day Show,' and 'Kevin Eldon Will See You Now,' all produced by 'BBC Radio 4.'
In 2003, Catherine was seen as ‘Charlotte Lewis’ in the 'BBC One' series 'Servants.' She was cast as ‘April’ in the 'Channel 4' sitcom 'Peep Show.' She first appeared in a 2004 episode of the British sitcom and later reprised the role in four episodes in 2015. Catherine had a brief role in the 2007 British comedy film 'Magicians.'
From 2007 to 2012, she played various characters in the British sketch comedy 'Ruddy Hell! It's Harry & Paul' (also 'Harry & Paul'). She was featured in various roles in two British sketch comedy series: 'E4’s 'Dog Face' and ‘BBC Two’s 'The Peter Serafinowicz Show.' She also appeared in an episode of the 'BBC Two’ science-fiction sitcom 'Hyperdrive.' In the subsequent years, Catherine appeared in the British TV series 'Trexx and Flipside' (as ‘Miss Olsen’), 'Lead Balloon' (as ‘Sandra’), 'No Signal,' and 'Comedy Lab' (as ‘Maya’). She also worked in the 2010 comedy TV movie 'D.O.A' (as ‘Lucy Carrington’).
Catherine wrote and directed the 2011 comedy short 'See Me.' That year, she starred opposite Rob Jarvis in the comedy short 'One Man.' In 2012, Catherine essayed the role of ‘Head Chef Celestine’ in the British–American black comedy series 'The Increasingly Poor Decisions of Todd Margaret.' She then appeared as ‘Sarah’ in the ‘Sky Living' comedy series 'Gates.'
In 2014, Catherine relived her characters from 'Harry & Paul' in 'Harry & Paul's Story of the 2s.' The TV movie marked the 50th anniversary of the 'BBC Two' series. The same year, Catherine was seen on the big screen after years. She starred in the 2014 live-action animated comedy 'Paddington.' Catherine played a mother in its sequel, 'Paddington 2,' released in 2017.
In 2015, a formal announcement stated that Gemma Arterton had been roped in for Catherine’s directorial debut feature, 'Like a Virgin.' It was produced by Kate Ogborn. Catherine collaborated with the 'British Film Institute' for the project. She played the character ‘Julie’ in the 2016 TV film 'The Comic Strip Presents Redtop.'
In 2018, Catherine got the most significant role of her career. She was cast as ‘Sally,’ the titular role in the British comedy series 'Sally4Ever,' alongside Julia Davis and Alex Macqueen. In addition to TV, radio, and films, Catherine has been active in the theater circuit as well. She has co-written and directed a few plays such as 'Overtired and Showing Off,' 'Dance with Me (Be Mine),' and 'Friends and Family' (also credited as a performer). Her other theater credits include 'The Edinburgh Comedy Revue' (co-writer), 'C'est Magique' (co-writer), and 'Mapping the city' (performer). The play 'Your Whole Life,’ co-written by Catherine and performed at the 'Traverse Theatre,' won a 'Sunday Lizard' award.