The brave TV star, 66, was diagnosed with colon cancer in July 2013, and the disease has since spread to her lungs and liver.
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Lynda Bellingham has decided to end her cancer treatment in November
In her autobiography – serialised in the Mail on Sunday – Lynda said, "August 13, 2014. Yesterday was the glorious 12th – a day for us to remember because it is also the day I decided when I will die. I am very dramatic, aren't I?
"I know it's not ultimately my decision, but it is my last vestige of control to sit in front of the oncologist and say when I would like to stop having chemo and let the natural way do its thing.
"I sat down with (husband) Michael and Professor Stebbing and announced: 'The time has come for me to cease and desist.'
"I would love to make one more Christmas, if possible, but I want to stop taking chemo around November in order to pass away by the end of January."
Lynda Bellingham and her husband Michael pictured at Buckingham Palace in March
Lynda also shared her hopes that her third husband Michael, who she married in 2008, finds happiness after she is gone.
"I don't want to leave my husband, because I know he is going to be so lonely," she said. "I know the children will rally round, but he can be a cantankerous old bugger at times.
"I would hope, in a way, that Michael does meet a lovely lady, who could look after him and they could have a loving relationship. He says he doesn't even want that again, and I understand, but things can happen."
Lynda received an OBE from Buckingham Palace earlier this year, in recognition for a career that has spanned 40 years. Her autobiography, Memoir, will be published on 9 October.