A good result for you and your children, if rather late. I would press children's services for an apology and an explanation of how it could go so badly wrong.
Thank you for offering to stay on here and help - it's always good to have people on here who have been through the worst but still got a good result, it inspires other dads that all in not lost.
I would consider speaking to the Family Rights Group or your local MP about raising a complaint with the Parliamentary Ombudsman on the matter.
Great to hear that your children are now safe and well with you and thank you for keeping us updated. Please do stay around and keep posting.
Great job and well done...you and your children can now look forward to a happy and settled future.
I agree with Yoda, make an official complaint to Childrens Services and then make an appointment to go and see your MP to ask for it to be escalated to the Parliamentary Ombudsman. You could also complain to OFSTED as they have a duty to hold government authorities to account....unfortunately nothing can take away the hurt of their failure to your children but perhaps the can be made to improve their services for future children who need their help.
As I said before, children are so much more resilient than we think and I'm sure your children will get over this and go from strength to strength under your care.
All the best