You need to apply to your council. Mine will only cover 75% of my bill, so I would need to pay the rest. Each council is slightly different, so check their webpages.
I'm sure if you contact them, and explain it was a genuine oversight - they'll appreciate your honesty, and will adjust things accordingly. That's what I would expect anyways.
Chris.
Nothing on this board constitutes legal advice - always consult a professional about specific problems
After your prompt, I dug out my ESA500s from 2012 to 2024 (!!) to ensure I will get the ESA(New) without any additional drama when forced to move to UC later this year.
I also printed off my 'pension forecast' which has all my NI contributions since dot. As they seem to love hacking Disability Benefits, it may help us in the longer term...