Family-friendly places in China?

Hello, my husband has been offered a job in China. We have been given the option of Shanghai or Beijing. We currently live in a very rural part of the UK. I myself am not very well traveled and will intend to travel back home to the UK several times during the year as I'll get home sick! We have a 4 year old and 1 year old. I intend to be an at home mum so won't need any schooling, although I may look into the children learning the language when we are settled. I will be treating this an as an adventure so will want to plan several things during the week, be it mother and children group meetings, activities, attractions for children, etc. Firstly, which city would be better suited to us? Secondly, which parts of the city offer the best British community for support and friendship? Thanks hugely.