Good for you Andy.
As everyone has said, get your main points down on a piece of paper.
The system is discriminatory. If you were Polish and working here you could bring your filipino wife and child here and pay nothing for the Visa.
The £18600 is not right or fair as there regional pay differences in the country and living costs vary so much depending on where you live.
I would also mention how you work in the NHS and your daughter serves this country in Afghanistan and yet this same government is putting up barriers to your right to a family life.
The bottom line my friend is you are British and in love with a woman whom you have married and want to spend the rest of your life with and this government is preventing you from doing this.
As a listener I'm sure it would appeal more to me to hear the emotional side to this story. A husband and wife very much in love kept apart by ridiculous Government Policies.
Best of Luck matey
