Code Kingdoms runs in the web browser, and so will run fine on iPads & Android tablets. It’s free to use, and easy to set up teacher and child logins.
Their lesson plans and resources are tied directly to the new Computing curriculum enabling teachers to use Code Kingdoms purposefully in their classrooms. You can download them for free here. If you’re in London you can even get someone from Code Kingdoms to visit your school to deliver a free workshop!
The site is still in development, but there’s a lot there already for children to use.
Take a look here and see what you think codekingdoms.com