At this price point, I'd go with the old shape Suzuki Swift 1.2 petrol. It has an excellent reputation for reliability and has space for two child seats in the back. But you'll need a five-door model, otherwise, you'll need to slide the front seat forwards/backwards each time you want to get your children in/out of the car.

For our Suzuki Swift review, see: www.honestjohn.co.uk/carbycar/suzuki/swift-2010/