If the Health Insurance Board, as created by this subchapter, does not, prior to December 31, 1971, implement a health insurance plan in accordance with the provisions of this subchapter; then and in that event, any group or groups of Government employees may propose a health insurance plan or plans to the Governor and the Legislature. When such plan or plans have been approved by the Governor and the Legislature, the Government shall contribute to the cost thereof in accordance with section 638 of this chapter.