The comedienne said she hopes the movie, titled Edina and Patsy, will be made by the end of 2015.
The film will follow the sitcom’s two main characters, played by Saunders and Joanna Lumley, and will reportedly begin with the flash friends waking up hung-over on an oligarch’s deserted yacht.
Saunders told the Sunday People: “I’ve finished the first draft. I’m feeling euphoric. My proper New Year’s resolution is to do the film, otherwise it’ll be a pointless year of procrastination.”
The long-running comedy series, which began in 1992, has spawned a number of hour-long TV specials but has yet to reach the big screen.
Best films to watch in 2015
Best films to watch in 2015
1/9 Suffragette - 11 September
Meryl Streep is bound to make a formidable Emmeline Pankhurst in Sarah Gavron's new film about the British women's suffragette movement of the early 20th century. Streep is again working from a screenplay by Abi Morgan who also wrote The Iron Lady.
2/9 Far From The Madding Crowd - 1 May
Thomas Vinterberg turns his hand to Thomas Hardy and British costume drama. Memories of the John Schlesinger version with Alan Bates and Julie Christie will be hard to exorcise. Carey Mulligan and the mercurial Flemish actor Matthias Schoenaerts star as Bathsheba Everdene and Gabriel Oak.
3/9 Jurassic World - 12 June
The third Jurassic Park sequel is finally here starring Chris Pratt. The storyline goes something like this - theme park gets dinosaur to attrack visitors and it all goes horribly wrong. Should prove a fun one among cinema-goers.
4/9 Terminator: Genisys - 3 July
Arnold Schwarzenegger kept his promise - he's back and he's trying to stop Judgement Day.
5/9 Spectre - 6 November
Bond is back for the 24th time. So is arch-villain Blofeld. Director Sam Mendes did a sterling job with Skyfall but the last movie ended on a very downbeat note with poor old Judi Dench signing out of the series. The challenge now is to reinvigorate a franchise that is already well into its 50s.
6/9 Cake - 20 February
It's Rachel from Friends as you've never seen her before as Jennifer Aniston plays Claire Bennett - a woman who initiates a relationship with a widower while battling hallucinations of his dead wife.
7/9 Suite Francaise - 13 March
It will be intriguing to see how Saul Dibb’s long-awaited adaptation of Irène Némirovsky’s novel deals with a problem that has often confounded British film-makers: how to portray French characters played by English-speaking actors in Nazi-occupied, wartime Paris without slipping into ’Allo ’Allo!-style caricature. Michelle Williams and Kristin Scott Thomas lead Dibb’s promising cast.
8/9 In The Heart Of The Sea - 13 March
Chris Hemsworth plays tough seafarer Owen Chase in this dramatic Moby Dick movie.
9/9 Cinderella - 27 March
Kenneth Branagh's live action remake of Disney's classic tale stars Downton Abbey's Lily James. Helena Bonham-Carter and Cate Blanchett also star as the Fairy Godmother and evil stepmother.
Absolutely Fabulous returned for three one-hour specials to mark the show’s 20th anniversary on 25 December 2011, 1 January 2012 and 23 July 2012.
The cast for the film has yet to be confirmed, but it is thought it will include the comedy’s long-standing stars Julia Sawalha, who plays Edina’s long-suffering daughter Saffy, Jane Horrocks and June Whitfield.