You asked

My child receives extra help in primary school. What should I look for in a secondary school?

If your child eceived support and assistance in primary school,you will need to look for a secondary school that has a special education teacher in place on a full-time basis that is able to offer support to any children with special needs.
The school should have teachers who have received training to teach children with special needs. It goes without saying that there should be an attitude on the part of all staff that your child is entitled to be a fully active school member and avail of all it has to offer.
 In order to find out if the school in question caters for all the above, you will need to speak to the school and ask these question. It’s important to bear in mind that your child may be eligible for special consideration at the time of Junior and Leaving Cert but this will be determined about a year before these exams will be taken.

More questions

Your child will have an Individual education plan that outlines exactly what services your child will receive.
Any child who received special education resources or support in primary school will almost certainly be eligible for the same support in secondary schools.
If your child has been receiving extra help in primary school it is important to look for a secondary school that will suit his needs
There are significant differences between children who are slow learners and children who have a learning difficulty?
There are lots of things you can do to help your dyslexic child develop their reading skills.
It's perfectly normal for parents of children with ADHD to worry about their child's future. 
Teenager's with ADHD will require additional support and supervision from parents to avoid behaviour problems.
There is no single, easy way to treat ADHD. Treatment is made up of a mixture of medication, parent training, counselling and a special education environment.
ADHD is generally diagnosed when a number of the symptoms outlined before the age of seven and for a period of more than 6 months. 
There are many different behaviours which are characteristic of ADHD: