Thanks for the responses and good advice. She's keen to have a go on a bike, she's watched me on them for years and asked me if she could learn. Whether trials will be her thing i am not sure, but i'm taking her to a local trials club soon so she can see whats trials riding is like and decide for herself.
If she wants to give it a go I will find somewhere she can get a try one out with some basic training and see if she gets the bug. The oset 20 looks a great bike for a child or beginner to start on so i'll keep those in mind if she's serious about it.
Cheers