I assume you are UK based since you use metric dimensions.
My wildlife pond is plants, planted loose, in soil, straight over the
liner with the exception of where there are large folds, there I put a
flat layer of plastic over the liner so that the roots cant get into
the fold. Personally I am very pleased with the result.
What Koi-lo says about the roots growing all together is true but, with
the exception of reeds (possibly norfolk reed) and Typha latifolia,
reedmace or cattails (frequently incorrectly called bull rush) that
doesnt bother me, I should have potted the reeds and cattails in solid
containers.
Re making it animal friendly, I would suggest that you ramp the soil on
the shelf so that it breaks the surface within an inch or so of the edge
of the pond, if you dont want it breaking the surface then bring it to
within 1/2" or slightly less of the surface. My shallow shelf is about
2" to the liner and the soil breaks the surface, I think it would have
been deeper to the liner with a suitably thicker layer of soil.
If you are UK and you want fish I would stock the pond with either
minnows or sticklebacks, my stickle backs jumped into a suitable
container whilst I was walking in a feeder stream for a local
resevoir.

DO NOT add the plant Tillaea recurva, Crassula helmsii, australian
stone crop, http://tinyurl.com/kwz43 its chuffing invasive and can
smother more desirable plants

My pond is not filtered but there is a pump driving a small stream. I
do not feed the fish in the pond apart from once in a blue moon with
any mosquito larvae I find elsewhere in the garden.
If you do like wise then until the higher plants become established
expect the pond to be thick with blanket weed but since the end of my
first season I have not had any blanket weed. I added the floater
azolla during the first summer and that thrived but again since the
higher plants became established the azolla barely ticks over and I
would doubt it I have more than 6" square of it. If you use azolla
during your first season and harvest any of it COMPOST the crop do NOT
throw it out. I would suggest you harvest it once you see it start to
turn red, it can die off and sink rather quickly and in another pond
which was totally covered by a thick layer of it the decaying material
on the bottom of the pond could be smelt in the air around the pond and
would probably kill any animal life in there.

My pond is surrounded by turf, small amphibians, in my case froglets,
can stick to hot dry concrete and probably rocks, they will then
dehydrate and die. The only way they can be released with out skinning
them is to soak the concrete with water.

How are you thinking of 'land scaping' around your pond?
What plants are you thinking of? Lilies my be inadvisable depending on
how wild you want your pond to be, they may not like winter and early
sppring competition for light whilst 'running' on over wintering pads.
I suggest you stick largely to native plants.




--
sean mckinney