UKF application for 17 yr old with unmarried British father

I'm hoping for some advice re UKf applications, and suggestions for our predicament. I am Australian and my husband is British. We have been in a de facto relationship for 30 yeArs and living in Australia. We have a 17 year old Australian born daughter who has just arrived in UK for her gap year (on a holiday visa) stopping with an aunt. Her aunt had lined up some part time work for her. We were devastated to discover soon after her arrival that her application for a British passport had been refused because we are in a de facto relationship. (Yes we should have read form more carefully but in 2 calls to PAssport Office to clarify about de facto we were told there would be no problem. Another follow up call and the employee had to ask a supervisor what de facto meant!) we have since located the UKF form and are about to lodge application. My questions are:

1. Home Office told us 3 to 6 months for a response - is that your experience?
2. Would applying for settlement in UK be a quicker option? (To allow her to work sooner.?) website shows a same day processing option - has anyone had any experience with this?
3. Any advice gratefully received as to how we get quickly establish our daughter to work legally in the UK.

B
cheers, SuzieG

Do you have a British born parent?

If you do, your daughter can apply for a UK Ancestry visa without much fuss.