Are you sure the cost will prohibit him from going on to college. He may be eligible for the higher rate of maintenance grant and be exempt from the high administration charge which is currently payable at the start of the academic year.
Worth looking into before dismissing the idea. People on lone parents allowance 'were' eligible to keep their payments if they had a child at college under the age of 23, don't know if this still applies or not after all the recent budget changes .