So, the pond design isn't meant to be a concrete pool made to look like a pond, I have deliberately not made it as such by leaving the bottom of the pond and the upper ledge and edges free of concrete, this allows the water to rise and fall naturally, plus gives the animals, fish and whatnot somewhere to dig about.
I will put in rocks and gravel on the concrete ledge where the plant cages will go for the fishes to make nests in and around at a later date, before I plant it up.
The concrete sides to the pond were really just an idea I had to consolidate the sloped sides of the pond, in order to stop slumping during rains, but also where fish and animals burrow along the water line into the mud bank.
Fish also have a tendency to root about in the mud at the base of plants, uprooting plants as they do so, by putting plants such as waterlillies and such in baskets/cages containing soil and gravel, topped with a mesh and more gravel, this will protect the plants, but also allow for them to be moved about to optimal effect, plus I will be able to control plant growth easier. Lillies also need to be started off in shallow water and then moved to deeper water as they get bigger, so this also solves this problem.
The concrete pipes sticking out of the side are not so that water can drain out of the pond as they are below the intended water line (although this will happen to some extent), but rather the other way around, so that ground water can seep in without breaking off the concrete I had put around on the sides.
As the water level will fall during periods of no rain, I'll have to top-up from a hose every day or so.
Anyhow, here's a pic of the partially concreted pond, complete with access steps on the left. As you can see, I have also put in a barbed wire fence to keep cattle out. Eventually I'll use plants, low walls and other devices to create a perimeter, but for now this'll do.