If you were 9 months on the dole before you went to college, you would qualify for BTEA, rent allowance and would get the local authority grant as well as a top up grant because you are receiving social welfare payments. Think the grant works out about 15K in total for the year as well as BTEA.
If you stay working until you start college you will get the grant without the top up which is about 9k. When you apply for the grant you are means tested but mature students automatically qualify (most of the time) for the higher rate. The grant forms would be out around June if I remember correctly. Its a good idea to be getting your paperwork together (P60, balancing statement, proof of residence etc) for it in the mean time because the sooner you send it back, the better because then you wont have to pay for fees when you register for college and spend months waiting for them to be refunded.