The 69-year-old actress, who plays Patsy Stone, has revealed she will begin work on the eagerly anticipated feature film in October, after her co-star Jennifer Saunders completed the script.

She revealed: ''She has written it, and it'd be wrong for me to say that I've completely read it because I think it's been changing, but we are starting filming it on October 12th.''

The production will be the first time Patsy and her pal Edina Monsoon - played by Jennifer - have appeared in a feature-length film, having previously featured in fives series' of the BBC sitcom, which began in 1992.

Joanna - who today has launched the Spark Something Good initiative along with M&S CEO Marc Bolland, aimed at inspiring the British public to donate time to their local community - also teased fans will see all of the original cast return as well as special cameos, with the stars set to film in the south of France.

She explained: ''We are all there, the same old gang. Lots of people you will have seen in it before. I think we are going down to the south of France to do some of the shooting there ... It'll all be shot on location. It is going to be ravishingly funny! Very gorgeous and completely fabulous!''

And although the star has spent years sporadically reprising her role as the chain-smoking socialite, she admitted her classic beehive hairstyle would be too annoying to achieve each day so is planning on wearing a wig.

Speaking on ITV's 'This Morning', she said: ''I usually use my own hair, and that's usually for one show a week in front of an audience, but when you're shooting for seven or eight weeks every day, I think I'll give it a bit of a break. Jennifer calls it Mr Whippy!''