The Irish secondary school cycle is generally 5 or 6 years long. Children begin their secondary school studies around the age of 12 - a year later than th UK. Normally they leave around the age of 17 or 18, having taken two state exams in that period.

The secondary school year goes from the first week in September to the first week in June. A much shorter year than the UK . However if your child is taking exams they will not finish until the end of June.
Irish language is compulsory if your child was under 11 when they moved to Ireland.

It is a very exam focused system in Ireland - which might suit some people but not others.
At the end of the 3rd year pupils take the Junior Certificate exam. There are a number of subjects covered - some options are available. Surprisingly I.T.is not a separate subject.

Most schools offer students the option of a Transition Year after they have completed the Junior Cert. This allows students to explore other non-academic interests, whether they are social, creative or linked to the world of business. It gives them a chance to look around and to mature before taking moving into the Senior Cycle, which will lead them to the final Leaving Certificate exam.
Most students take 7 subjects in the Leaving Cert.

Students may choose from 3 different Leaving Certificate programmes. They can take the traditional Leaving Certificate or they can choose from the Leaving Certificate Vocational Programme or the Leaving Certificate Applied Programme, both of which focus on a student's more practical and technical abilities

Secondary Education is free in Ireland - unless of course you choose one of the Private schools.
But you will need to pay for school books and uniforms. Usually, you will also have to pay for extra-curricular activities. People with a medical card or on certain benefits can get a "back to school" grant for each child to help pay for books etc. Transport to school is subsidised and is relatively cheap. People on low incomes who qualify for Medical Cards will get free transport.