Your son's right to access UK student finance is not linked to your employment in the north/UK. As a non-UK resident your son is generally only entitled to a student loan towards fees from the UK, not maintenance support whether this be a grant or a loan. As a Republic of Ireland resident he can of course, subject to your household income, qualify for a higher education grant towards his maintenance from Donegal County Council. In addition if he is employed in the UK he can asked to be treated as a "migrant worker" and to be considered for the above additional forms of student finance (loan and/or grant towards maintenance) by the Education Authroity attached to his college in Cardiff. If he begins part-time work he should approach the college's Student Welfare officer regarding applying for this.