Jane Tomlinson has run a series of gruelling races

Mrs Tomlinson, 40, of Rothwell, Leeds, has already raised more than �500,000 for charity by taking part in a number of gruelling events.

On Monday she will start her biggest challenge yet in which she hopes to cycle 2,500 miles in 35 days.

She aims to ride a tandem with her brother Luke Goward from St Peter's Square to her home.

The trek, with only one rest day, includes a ride up the 6,555ft Mont Ventoux - one of the legendary climbs of the Tour de France.

The journey will include an average daily ride of 75 miles with a few long days of 120 miles.

Mrs Tomlinson's first week of cycling takes her through Italy, before heading into Monaco and France.

The first week of the trip will take them through most of Italy

On Sunday, Mrs Tomlinson, a mother-of-three, said: "I'm feeling very very anxious this morning. I'm in quite a lot of pain and am very worried about the start tomorrow.

"I have 55-miles to cycle on Monday and at the moment I'm struggling just to sit up."

Mrs Tomlinson is no stranger to cycling.

She and Luke have already completed a 1,060-mile bike ride from John O'Groats to Land's End.

In April she completed the London marathon and in March she ran the York half-marathon, only 10 days after finishing an intensive course of chemotherapy.

Mrs Tomlinson hopes to arrive in Monaco on 13 May, before setting off to Paris which she hopes to reach on 26 May.

She is due back home in Leeds on 7 June.

Since being diagnosed with terminal cancer three-and-a-half years ago, Mrs Tomlinson has defied doctors who told her she had only months to live.