In some cases student's can be eligible for the postgraduate loan whilst receiving funding from another source. However if a student is in receipt of any of the below funding, they will be ineligible to apply for the loan.
Research Council (RC) studentships, stipends, scholarships and tuition fee support
Social work bursary
Educational Psychology Bursary and their course starts on or after 1st August 2020
National Institute for Health Research bursary
Hope this helps.