The basic rules for a disabled reduction from Council Tax are:
if you need an extra room in your house because of a disability (this could be eg a bedroom for a carer, a downstairs bathroom in addition to an upstairs one, a room for kidney dialysis, or an extra room for some other reason. They include an extra kitchen in this category but I can’t think what for, unless you have someone who is very sensitive to certain normal food ingredients, such as severe coeliac disease)
or if a disabled person uses a wheelchair in the house (so might need wider doorways, more space, etc)
And a disabled person lives in the property as their main home, you will qualify for a reduction in Council Tax to the band beneath the one your house is currently rated at. If your property is already in Band A, the lowest band, you get a percentage reduction, I think it might be something like one sixth of the charge (or thereabouts).
your property has to be inspected to ensure it fits the criteria, but it’s really very straightforward, an officer just come to look at the house and then will arrange the reduction.
Each year you then get sent a form to complete to ensure you still qualify, but that’s it.
Its worth claiming if you think you might fit the criteria, just contact your local Council or check their website if you don’t still have all the leaflets sent with your Council Tax bill.