I am unemployed on Jobseekers Benefit (�ire).. how much Child Support should I be paying to my ex in the U.K?

Let your wife take it through the CSA, you will have to pay �5 a week, that will be taken directly from the benefit. She won't get it backdated as the csa only works from the date you put the claim in. Some mothers assume they will get more going through the CSA but it doesn't always work that way, I know it put my partners payments down when she decided to go that route thinking she'd get more.