I am a bit confused about your pond. You say it is a wildlife pond, which makes me think gently sloping sides for birds, amphibians, hedgehogs, etc. to safely drink/bathe, etc. but then you say it is raised. Does that mean it has straight sides?
I have some small ponds, made out of large plant tubs, which do have straight sides, but I have made a sort of brick staircase inside the side of each, as well as a shallow ‘beach’ area, so that any animal/bird can get out easily. The ‘beach’ area is made of one of those (fairly large) aquatic plant baskets full of stones (standing on more bricks) and the water above that area is always shallow. On a larger scale you could use some sort of larger container in a similar way. One of these ‘ponds’ is sunk into the ground and the hedgehogs often drink from it, but the others are free standing. The hogs probably couldn’t access the free standing ones, but I have included ‘escape routes’ in those as well, just in case and also for the birds.
The following is a link to the garden features page of Hedgehogs Street, which does suggest using chicken wire, but doesn’t mention using a plank as well.