Who told you your Father wanted nothing to do with you?
I spent 18 months and £4000 taking my ex to Court so I could see my children, over that 18 months (when she wouldnt allow me to see them at all) she filled their heads with all the "your father hates you", "your Father doesnt want to see you" etc lies which took a lot of sorting out on my part.
If you take what you are told by your Mother (and her side of the Family) as gospel then that is your prerogative but unless your Father told you himself that he didnt want to see you, well you work it out!
I can certainly see where you're coming from there, however I have made a point of at least trying to build up some kind of a relationship with him and he just doesn't seem interested.
Also I'm pleased to say my mother hasn't tried to stop me attempting to salvage something, although I'd take any one-sided stories with a pinch of salt, as your story shows how much people will attempt to skew their children's viewpoint in this situation
Perhaps the whole CSA thing hasn't helped on that front..
Does he own a home/property? The CSA will get a charging order against a property on the land registry if pushed hard enough.
He owns a property, but it's a joint mortgage, IIRC this was a stumbling block.