A win against Russia in their last pool match will power them into the final and Barnett believes England's second string, who are yet to concede a point, can still improve.
Barnett said: "In the first half we were very dominant and I think the Netherlands were shell-shocked.
"However, they started to tackle well after the break and we made more mistakes, though they still never really challenged our line.
"It's good that we have not conceded any points again; that is important to us.
"We wanted a good record in the early stages of this tournament and we have that.
"Next up is Russia on Wednesday so we have got a lot of work to do in a short turnaround again, but we will go into the game feeling confident."
Bristol flanker Marlie Packer set the tone for England with a first-minute try and club-mate Nicola Hoole got the first of her two scores four minutes later.
Richmond's Kay Wilson then outpaced the Netherlands defence for her second try of the tournament before Hunt, Tamara Taylor and Hoole wrapped up England's scoring inside 30 minutes.