Andy
The SMI loan is wholly dependant on your receiving an income-related benefit such as ESA(IR) or Pension Credit, so if you do not qualify for PC then the load will be stopped although it does not become repayable/
Talk to your Local Authority about the discount, at the moment I imagine it is enabled by your SG award but there may be alternative, for example; have you looked at whether you would be eligible for PIP?
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems