Thanks everyone for your replies. I understand that children have to enjoy themselves and I'm not really disputing the noise issues, dog Barking alongside kids shouting etc (I can play radio or headphones if outside alone). She is a registered child minder so no doubt it'll will be used often!
I'm on decent terms with her which makes it even more annoying that she didn't mention it to us.
We're currently re modelling our garden, ie new fence on other side of the garden, new shed location, vegetables patch etc and have consulted both neighbours on each side of our plans out of neighbourly manners.
I wish I could upload pictures to show you what Im trying to explain.
It's right outside my patio doors and decking area and it appears that the previous owners of my house must've had issues with them as our existing fence on this side appears to be over 2m and hastily erected with virtually no spacing between panels. So any plants/screen will need to reach at least 12ft and then I'm concerned that they could chop the tops off as it might actually touch their safety netting, it's that close, less than 1/2 ft away from fence.
I was thinking about asking them to either try moving it further back from the fence or to put up a trellis or green netting as to alleviate the overlooking aspect.
If she refuses then it looks like bamboo in containers is the way to go although as someone mentioned can be costly. I don't really want traditional hedging at that position as it could block out light on our decking plus.
Thanks Pp for that link, very interesting as I've been trying to find any legal info.