The Children Act (section

states that a residence order is just that - defining the child's place of residence. If the children already live with her, then nothing will change. If you currently have parental responsibility then you will continue to have a right to be in your children's lives daily, talk to and have reports from their school, etc. You will have access to their gp's records and you will have to be told about major things (like if your children start to attend counselling, etc).
If you don't have parental responsibility, then you are no further ahead at the minute anyways. A residence order has some restrictions on the resident parent that they don't have otherwise. Like your ex can't change your child's name without your consent (as long as you have PR), nor can she have them known by any other name (like at school). Also, she cannot take them out of the jurisdiction for longer than a month without your consent (again if you have PR).
Actd is right about changing residence - the Court will only do that under exceptional circumstances and if there is a question about residency then Cafcass will become involved, and Cafcass everywhere are having difficulties, as I've read in the Guardian and The Times recently, with backlogs.