I suggest he apply for a social services (SS) assessment for care and support under The Care Act 2014. Even if he has to pay for the care himself, it still needs assessment. SS will inform him, they will do a financial assessment and if he has savings over £23,250, then he would have to pay for care in full, savings below that is on a sliding scale for charges down to around £14,000. Below that and care is free. Then, when it’s under way, he should ask the social worker to fill in for him the NHS Screening Checklist for Continuing Healthcare Funding:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1099597/NHS-Continuing-Healthcare-Checklist-guidance-2022.pdf
If a person’s needs for care arises from a primary health condition, as his will, then he can be assessed to see if he meets the criteria for Continuing Healthcare Funding (CHC). The NHS is free at the point of use, and CHC funding for care is likewise free. There is no means testing for CHC - how much money or what other assets he has, are irrelevant.
People who have terminal conditions, with less than 6 months to live, can be Fast Tracked. That won’t apply yet, from what you say OP; but even if he doesn’t meet the criteria now, he could reapply later, as the condition progresses.
I’d also look into applying for PIP, and even if he’s not affected enough yet to qualify, that too can be Fast Tracked for people with less than 6 months to live.