If this job you want prayer about is right, which it sounds like it is, then I can assure you that God will provide you with confidance, and peace about the interview, all you need to do is ask him to give you confidance and peace, and as you've mentioned through worry you've not slept, he will give you that also. Give the Lord your worries and concerns, put them in his hands and ask him to lead the way. Particularly at night pray that you will sleep peacefully, and not worry. God knows what is right for you and if this is the right move then he will guide you in it.

I will also pray for peace of mind for you.
Jane (Im-revived)