Badgeman,
Being able to speak German at a proficient level is a good start, although you mention that your mum is german citizen, are you? Without an EU passport you won't have a chance. And to be honest LH can be so picky about who they take, anything less than a German passport will probably kill your hopes.
As far as the JAR exams and license is concerned, it's going to cost you around US$15-20,000 to complete at todays horendous exchange rate and about 8 months minimum. That's if you study like a loony and get all the flying done asap.
LH has always been extremely difficult to get into if you're standing on the outside looking in................