Eweleaze is a bit marmitey on here - some love it, some absolutely hate it. I am one of the lovers. We didn't go last year and won't be this year and I am really getting withdrawal symptoms. We and friends are planning to definitely go again next year.
It is difficult to say for sure where to head. We have always picked Point Field as there are flat bits as well as slopey bits, it is one of the car free fields (although you can drive in and out to drop off stuff and pack up again) and that makes it a bit safer for young children. I wouldn't camp right by the cliff edge with small children (although we did on a non-steep spot and were fine) but there are lots of nice spots all round the field to choose.
It isn't the field with the best views from each pitch (that is probably East Field) but then, it isn't so slopey either.
Admittedly, the toilets in Point Field are compost (I think many of them are but nearer the car park there are regular loos) but we found them ok and kids didn't seem to mind. Might be worth bringing a potty/bucket for your tent in case they do take against them.
Generally though, Eweleaze is little kid heaven. There are loads of hay bales to jump on - including a barn with them for rainy days, loads of animals including guinea pigs to hold and pet and even puppy walking for them to join in with. Eweleaze has its own beach (albeit stoney so bring water shoes) which you can access down steps from (I think) East Field. There is also a nice walk to a local pub that does great food, although with small children you might want to drive.
I have a feeling they may have introduced some other stuff since we were last there.
Fingers crossed you will love it, and your children definitely will.
One word of warning. It can get very windy. If you have a gazebo or event shelter and wind is forecast, it might be worth taking it down at night (or removing the fabric in the case of an event shelter) as it is not uncommon to get up in the morning after a windy night and find some very mangled awnings and shelters lying around.