http://www.nhs.uk/chq/pages/1087.aspx?categoryid=68&subcategoryid=162"If you move to the UK, you will not be charged for NHS hospital treatment from the date that you arrive as long as:
- you intend to live permanently in the UK, and
- you have the right to live permanently in the UK or have a "route to settlement" that will allow permanent residence in due course
You'll be expected to prove that you meet these requirements.
Your spouse or civil partner and children under the age of 16 (under 19 if in full-time education) are also exempt from these charges if they live with you permanently.
If you're not entitled to live in the UK permanently but you've applied to the Home Office to enter or stay, you'll be charged for hospital treatment until:
- your application is granted, or
- you have 12 months' lawful residence in the UK"
This would appear to imply that provided you are in the UK on a visa with a path to permanent residence hospital care will be free at the point of use. I would take this to cover a spouse on a "family of settled person" visa since this provides a clear path to permanent residence.