Breech baby cesarian dates

Hi everyone My baby has been breech pretty much throughout pregnancy hes in an awkward position apparently to turn (transverse i believe). If hes still breech by monday they will be booking me in for an elective c section, Baby has a minor heart defect so they dont want him turned or a vaginal breech birth to avoid stress on him. In the uk what dates do they give you for a breech c section ? Would it be from 39 weeks or earlier ? Im currently 36+2.