How does the foster care system work in the UK?

I'm doing some research for a novel in which the protagonist is in foster care. I've already written most of the novel but I feel like I should make sure I've got my facts straight, so if anyone could explain to me kind of how it all works, I'd be really grateful! Do orphanages and Tracy Beaker style 'dumping grounds' still exist, how exactly do a family go about fostering you, what about contact with your birth parents? If there's no real likelihood of you being put back in their care, would you be adopted? Any other info would be appreciated too, if you think you've got something interesting!