Dame Esther Rantzen "joined Dignitas" after being diagnosed with cancer so she could end her life without pain.
The 83-year-old presenter was diagnosed with stage 4 lung cancer in January and is determined to have a "good death" so signed up for the controversial Swiss clinic in order to avoid spending her final days "dominated by pain".
Writing in The Times' Weekend magazine, she revealed: "I rang my local surgery to tell them my diagnosis and ask if they had links to a hospice nearby. I spoke to someone who was not my usual doctor, and when I explained my situation he accused me of 'catastrophising'. Slightly harsh, I thought.
"So I didn’t share with him the fact that I had joined Dignitas in case things got rough and I needed to fly to Zurich to end my life there.
"I can’t say my medical friends approve of that, but I know that having a bad death, one dominated by pain and other horrible symptoms, is dreadful for loved ones to witness, and that memory becomes a barrier blocking out other, happy ones.
"So I’m determined to do everything I can to try to achieve a good death, including flying to Zurich for a quick lethal dose of something, if necessary."
When she was first diagnosed with the disease, the former 'That's Life' host admitted she didn't expect to still be alive to see this Christmas, but has been amazed at the advance in treatment.
She wrote: "Frankly, I didn’t think I’d last this long. I’d had friends, like the wonderful Alan Coren, still greatly missed, who had been diagnosed with lung cancer then left us very swiftly, so last January I assumed that I would probably not be around for my birthday in June and that I’d definitely miss this Christmas.
"But when I met my oncologist I realised how ignorant I was and what gargantuan strides medicine has made recently.
"He told me that I could be treated. That having analysed my lump they would put me on a targeted medication: one pill a day with no serious side-effects.
" And that while it couldn’t cure my cancer, it could hold it back and delay it. Extraordinary news. And I’m still on that tablet and I’m still here.
"And when I last saw my oncologist and asked him if I am likely still to be around at Christmas he said, 'I’d be very disappointed if you aren’t.' "
To prepare for her death, Esther is trying to sort through all her possessions but gets easily distracted so will leave a lot of the sorting to be done after she's passed away.
She wrote: "Am I ready to go? Yes and no. The will is written, ramshackle furniture has been given away and old bits of technology have been dumped or recycled, but the barn is still full of boxes of files and scripts and photographs I should have sorted, filed or shredded long ago.
"But each box I open is so crammed with memories that once I start, I’m still reading it three hours later when I should have consigned it to a skip and moved on. I’ve decided to leave it all to my daughters to sort out."