You can arrange your own Turkish policy, check the wording as most don't cover serious illnesses such as cancer in the first year, many people been caught out...
And it has to be for in and out patients to satisfy the criteria. Policy prices depend on age and are dearer for women.
Sgk is 288tl for a married couple per month, and requires a medical at the Devlet.
For a 6 months residency they're accepting UK travel policies, but not for longer than 6 months.