Here are some UK resources:
He’s not in denial; he is so ill he does not know that he is experiencing symptoms of schizophrenia.
My advice is to try to get to the point where you are having the best days possible while he is not in treatment. If he ever becomes so ill that his behavior is unsafe, call the authorities again.
It’s not up to family members to treat this illness, but to get along with and love our relatives who have these illnesses. We’re not doctors. Your son would possibly benefit from injectable meds since meds seemed to help him in the past. Only a doctor can prescribe these.
Keep track of all the signs of his illness with dates so you can tell the doctor if they ever section him again.
Best to you