I'd definatly have an area set aside for butterflies etc, plenty of nectar type plants such as buddlea, rudbeckia, sedums etc, you can get loads of wild flower mixtures that are great for this type of thing.
There are organisations that will give projects like this some tree's to plant, i know my local council where doing something similar. I reckon if you got in touch with some organisations like the Forrestry commision you'd have some joy, check this link out
Woodland Trust