I read a novel a couple of years or so ago about a future United Kingdom where the government had banned unhealthy foods and basically anything enjoyable. Baking was illegal etc. The main protagonist was a woman.
This is "Bootleg" by Alex Shearer, published in 2003. Blurb from the back cover:
The Good For You party have come to power, forcing everyone to lead healthier lives and banning anything with sugar in it. Unable to cope without their beloved chocolate, Smudger and Huntly fight back and become bootleggers with local shopkeeper Mrs Bubby. But it's just a matter of time before the Good For You thugs catch them.
Mrs Bubby would be the protagonist you remember. She owns a grocery store and finds a forgotten supply of sugar and chocolate in her back room, so bakes cakes, which the boys distribute to buyers.
(I believe the party was elected due to voter apathy, but I'll have to check when I get more time to read!)