It's a fantastic place. I've been going for the last 15 years, generally camping here and I never get bored of it. You always seem to be within an hour of something to do, which is great.
For walking, try here Quite descriptive with a few photos to tempt you.
My wife loves it in Keswick. It's a 2 mile walk from where we camp, and we tend to walk halfway round Derwent water, then drink a bottle of champers next to the lake and watch the sun go down. You just can't get bored of that.
It is a family only one, no same sex groups, no noise after 10.30 and plenty of space for them to play. It is quite basic but with decent showers/wash area. Pub 5 metres down the track. And it is really cheap.