Jane Tomlinson has run a series of gruelling races

The 40-year-old will attempt to swim more than two miles, complete a 112-mile bike ride and run a marathon - despite being in hospital last week.

The mum-of-three said she planned to attempt the event even if it proved too difficult to finish.

Husband Mike, 43, said people should not assume Jane found the events easy - in fact they put her under strain.

He said: "Jane's dying an awfully painful death. Don't be misled by thinking because she does endurance events, she doesn't suffer.

"The training and races put a huge strain on her body constantly, leaving her in agony.

"Yet she still has to get to work daily and take annual leave to do the events."

Last week, Jane was admitted to casualty after pain caused her to lose her ability to walk or dress herself.

It is hoped that by taking part in the event she will reach her goal of raising �1m.

In October, she was honoured at the Woman of the Year Awards and was given an MBE by the Queen in 2002.

The Ironman begins at 12pm and continues for 17 hours.