Well the building reg's in Ireland state you must have a hearth. Extending at least 15cm either side of the stove/fire place and about 25 to the front. Our reg's are very similar to that in the UK so I doubt there will be much of a difference.
We have two kids at home. Eldest is nearly 2yrs old. We have a fire guard that goes around the whole hearth and has a small "roof" on it to stop him putting his hands over and near it. They don't really go near it but we always keep an eye on them.
This a pic of our fireguard (stock photo)