Sharon,
Ferry meadows c/c site there are two positioned both sides of the road that takes you into the actual Ferry Meadows Park.
One side is mainly hard standings, the other site is grass, with a superb childrens play area.
There are miles of traffic free cycle/walking paths within the park, the lakes are linked to the river nene which runs just outside the park.
There is the local nene railway line that runs along the side of park of the cc site , with a station short walk from the park, steam locos run during the school holidays/bank holidays and most weekends during the summer , which can take you into Peterborough.
We use this site a lot (our local)you need to book well in advance as weekends tend to be fully booked.
regarding your worry regarding your children and the lakes, some paths run parallel to the lakes , but there are plenty of bushes and trees between the paths and the actual lakes, not enough to spoil the views.Lots of water birds,(take plenty of bread) several children play areas within the park,also large areas of open grasslands.
Trust this quick description is enough for you and your family to enjoy all the facilties that this park has to offer,
Royston