If you haven't already, I think you need a solicitor - and quick. I'm not sure if you've uploaded all the correspondence you have received and what you have (#72) is difficult (for me) to see that it is from the same letter. How could page 1 be a fine from the court (which infers conviction and a fine / costs awarded against you) yet page 2 and 3 appear to relate to a court appearance this coming May?
If you haven't attended court at all, then the court will have no idea of your personal circumstances and apply a default methodology of collection of any fines / costs. You may wish to provide evidence of your financial circumstances that make it clear your income, fixed living costs (eg rent, travel costs(!), food, etc) so that they can see what your disposable income is. Payslips / bank statements will help you here, as will evidence of dependants (eg children). Only then can they reasonably be expected to change a repayment plan from the default to something more affordable (assuming the plan they have imposed is unaffordable to you).
If you can't afford a solicitor, then Citizen's Advice Bureau or even the court might be able to advise on how to engage in the process, but they are unlikely, unlike a solicitor, to be able to tell you what to say (for your benefit and best outcome).