Virtually impossible to get a visa like this since they changed the rules in July 2012 and made it very hard. We have only heard of perhaps 3-4 approvals since July 2012.
This is the criteria to be met and even then there is no guarantee of visa being granted.
https://www.gov.uk/join-family-in-uk/eligibility
Coming to be cared for - you’re an adult dependent relative
You must be dependent on a parent, grandchild, brother, sister, son or daughter of someone living permanently in the UK.
You must prove that:
you need long-term care to do everyday personal and household tasks
the care you need is not available or affordable in the country you live in
the person you’ll be joining in the UK will be able to support, accommodate and care for you without claiming public funds for at least 5 years
you’re 18 or over
The UK does not permit chain migration like the US does I think. If you choose to apply and pay the massive visa fees, including the NHS Surcharge of £1000 per person (£200 per year for 5 years payable upfront), and the visa is refused, the likehood of obtaining a visitor visa in future is zero as the intention to settle will be known.
