In order to be granted full residency then this has to be ordered by the court and I will provide information on how to do this. However you seem to be in a good position. If you have safeguarding concerns for the children then you can refuse to allow them to go with the mother. If you are going to take this approach and look at full residency then you must contact Cafcass and tell them what is happening. They will likely be instructed by the court to do a section 7 report and therefore by informing them you are getting ahead of the game so to speak. You will then want to make an application to the court for full residency. It is likely that if the court agree with you then they may ask for there to be supervised visits with the mother (you can express this as one of your wishes also).
In order to apply to the court, you will need to fill out and send form C100 (copy attached) with a cheque of £215 payable to HMCTS to your local family court centre. Or you can ring the court and pay over the phone (or pay in person if you go directly to the court and pay at the counter). If you are on low income/have low savings you can apply for a fee exemption here:
Once you apply the court will list a hearing where you and your ex attends. There will be a family advisor there too (from Cafcass) and if arrangements can be agreed then a consent order will be drawn up.
I hope this information has helped. You can find a local solicitor who deals with this on the law society webpage which is;
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