If there’s one feature you can introduce to your garden to help wildlife; it’s a pond. Almost regardless of how large a patch you have, introducing a bit of still water absolutely transforms your garden in terms of its value to living things.
One of the things you should be thinking about is making sure all creatures have access to the water resource. Make sure there are sloping banks. Make sure it’s not steep sided with nasty steep bricks to stop things getting in, or more importantly out. If a hedgehog falls into a pond and it can’t escape then it is going to drown. It’s got to be a place where creatures from the land can come and drink.