British Naturalisation

[Ubirajara]

Hi everyone
I am applying for British naturalisation and I am confused about some topics.
1- referee - if both referee can be British?
2- topic 1.49 page 10 Form AN - address of tax office or tax office reference, I am self employed and I can’t find this answer anywhere.
I would be very grateful if someone here could help me.
Thank you.

[CR001]

1. Yes they can and they must both be over 25 years of age and both be of good character.

2. Your UTR??

[Ubirajara]

I’m trying to sort it out but nobody knows if is the UTR the correct tax address.