Eligibility for a student health plan does not make you ineligible for Marketplace coverage and subsidies. Even if you are eligible for student health coverage, you can get coverage through the Marketplace. In addition, if your income is at least as high as the federal poverty level and you meet other requirements, you can qualify for premium tax credits; if your income is between 100% and 250% of the federal poverty level, you can also qualify for cost sharing reductions.
In addition, eligibility for a student health plan does not make you ineligible for Medicaid. Check with your state Marketplace to find out if you meet the income and other eligibility standards to enroll in Medicaid coverage.