My daughter has her fathers surname, we are not married but he is named on the birth certificate, she is about to start school and I do not want her confused with having a different surname to mine, can I change it without his permission as I know he will refuse??

Not legally. You would have to go to court to do so and he could fight it.

However, you can legally use any name you want to as long as there is no intent to defraud. When you register her for school, show them the birth certificate but explain to them that you want her to use your surname for for everything.

If I was a father, I would be crushed if my children used any other name but mine. Just a thought.