Blue badge - can someone advise on how the scheme works?

Hi I'm wondering if anyone can help me I'm stage4 terminal palliative care and wondered if anyone could advise in regards to the blue badge scheme.I do understand that there is a charge in regards but thought I read somewhere in special circumstances it waivers the charge.As hospital parking is so expensive and as its in my bones find it very hard to walk so the charge would be worth it please can someone confirm.Finding life really difficult at the moment not accepting its real thank you.