"People who don't have children imagine that their whole lives would be all right if they had children but they don't realise that having children gives you lots of problems; one is constantly worried," she said.
"Also I think it's impossible to be a mother without a huge sense of failure. Not that I think of my children as failures. I think they're wonderful, but one is always aware of what one isn't doing right.
"I was really helped by a friend recently because I was thinking, 'Oh God, I'm not strict enough', and also it's quite difficult ... John having died, obviously I overcompensate," she said.
"What I feel with all of them - because I've got three, really, with Phoebe, my stepdaughter, so it's 16, 17 and 18 - is that although I'm pretty easygoing about most things, I do think manners are important and being kind," she said.
"And they make me laugh - and that's quite important. So I like the people they are."
Lawson, who admitted trying on guests' clothes and putting on their perfume when she worked in a hotel in Florence after leaving school, has lost weight, having restricted her alcohol intake to Friday nights and discovered exercise.
But Lawson, whose first husband, mother and a younger sister all died of cancer, said: "I don't equate thinness with healthiness, as other people do, because I've only ever seen people get thin and then die."
- PAA