Reading app to share books with GC far away

I have been using an app called Caribu which allows me to read books to my GC in New Zealand. We can both see the books on our screens and see each other in a little window at the same time. It also has games we can play together, such as colouring in (more interesting games are available, but my eldest GC is only 2). There is a free version, but it soon runs out, so I took out a subscription. It is about £7.50 a month, and to be honest, the choice of books is not good (not to say there aren't a lot of them, but they are very American and not what I would call good quality).
So, my question, are there any similar apps out there that you use and would recommend?