Immigration for a child under guardianship

[race2015]

Hi everyone, I'm new to the site and I have an issue that I don't even know where to start with. I have British Citizenship and I have a non-British aunt in the Caribbean with a mental illness. She has a minor son (my cousin) and his father does not assist with him. A while back he was taken by social services and is effectively in care. The social worker and my aunt reached out to me and asked if I could assist by taking him to live with me. I'm willing to do this as I live alone, earn a decent salary and would genuinely like to help out. This issue is how do I do this regarding immigration matters? I know that if I adopt him he can gain status under mine however I'm reluctant to do this because (a) I do not yet have children of my own and this would create a line for inheritance (which I would prefer to keep clear for my potential children) and (b) it would interfere with his ability to inherit anything from his own father (who although does not support him now may later have some assets).

The social worker has suggested that she can have me appointed as a court ordered guardian for my cousin and this would also allow him the ability to live abroad with me. My question is, if I do this, how should I then apply for his immigration status? Could he be considered my dependent or would it be the student visa route and if so, would he be eligible to attend a state school or would I have to pay for a private school for him? Also is there anything else I should be considering? As much as I'm willing to do this, I'm trying to avoid it becoming a massively expensive and difficult process.

I would appreciate any help you can provide. Thanks in advance.