Depending on where you are taking your course -
my experience is that students can apply to the Co Dublin VEC, Tallaght, PLC Grant Section, for a PLC grant, which roughly amounts to around 135E per month paid directly into your bank account. If there are special circumstances you may qualify for an extra amount, up to around 180E pm. I can't say if this is the same with local VECs in all areas but you can check.
Income should be under c38K pa to qualify for a 100% grant, which reduces according to income up to max earnings of c48K pa.
Ask them to send you out an application form - in the case of Tallaght they only take calls on this subject between around 10.30 and 12.30 Mon/Friday.
If you have a medical card there is a good chance that you will qualify. Good luck in your course.