You should not go more than a mile from school - somewhere within walking distance. You can do this on 21st or 22nd June and at any time of the school day. You can concentrate on one or two organisms over a larger area, or all the organisms in a small area. Divide your class into groups to do different things.
Records can be any suitable form.
You might want to collect data about local weeds, invertebrates, or birds. The Action Kit has a list to choose from. For homework, you might want to use the information pages or the letter to young scientists as the basis of a piece of writing or research. There are some quotes, too, which give food for thought. The Action Kit also has a page of suggestions about how the children's results can be presented.