He's just tried calling the number to check entitlement to work at the Home Office to ask if he's entitled to NHS treatment. Their response? "Yeah, probably. Actually, we don't know".
If he has this letter from the Home Office, does this qualify as leave to enter? They seem to have no problem with his being in the UK whilst his application is being considered. Only on the Department of Health website it says:
"Under the current Regulations anyone who comes to the UK to take up permanent residence is fully exempt from charges for National Health Service (NHS) hospital treatment in England. A person who has been given leave to enter the UK by the Home Office to marry someone who is ordinarily resident here may be regarded as taking up permanent residence, and therefore exempt from charges for NHS hospital treatment."
Now I know they're not getting married, so they don't have a CoA, but they are applying as a durable relationship akin to marriage. Any thoughts?