Hi Velvet,
When we were there in May we found out about a pub called Idols, it does karaoke competitions between 8 and 10 for kids then afterwards for adults.
Unfortunately we only found out about this on our last day so didn't manage to get there but it sounded great.
Most pubs are child friendly, but we tended to stay in our Hotel as we liked the entertainment and the kids made friends there, we did get to Jimmys Karaoke bar a couple of times, they were great with our kids letting them get up to sing and everyone gets into the spirit of it giving kids big cheers when they are done. My son loved it!!
In Jimmy's they also had a hypnotist, he was brilliant, some of the jokes were a bit close to the bone but nothing obscene and my kids killed themselves laughing!!
If your kids are young it is maybe better in the hotels for them but as mine are 8 and 6 we found that they enjoyed themselves wherever we went.
Hope this helps,
Nicola.