Controlling stream erosion AND making homes for wildlife

Hi I've just moved into my new home in Berwickshire. Along one boundary is a beautiful stream. My neighbour has a line of very mature trees (20-30m maybe) mostly beech I think. On my side is mostly grass bank about 3-6ft from the water level. It runs through a channel where the sawmill (our garage) used to take power from the water. I'm longing to take care of my garden in a way that makes it as wildlife friendly as possible and this stream must have lots of potential. My concern is that there is quite a significant erosion problem on both banks. Some of the mature trees on my neighbours side are only 50% on land. On my side some chunks of bank have fallen during the thaw of this years heavy snow and some more is very badly undercut. Can anyone recommend the best plants to combine erosion control and provide good homes for wildlife? Thank you. Kathy