They’ve been suggested for Christmas - Gdcs are 6 and 7, and at the mo are doing homework/school activities e.g. DoodleMaths on parents’ phones. Parental controls are obv. a necessity!
I’ve looked online - there are masses to choose from.
This thread is a little old now, but if you’ve landed here looking for a kids' tablet, we’ve recently updated our best tablets for kids page with lots of great options, as tried and tested by Mumsnet users and their children. We hope you find it useful. 
MNHQ