Built the pond while volunteering at a NTS garden. We used blocks of peat to build the pond walls, easier to shape and piss easy to work with. I realise this is totally unhelpful for you but I'm no gypsy, so I've never built any sketchy **** with ****ey breeze blocks before.
Sorry, I forgot to ask, it says you are from the black country, do you know Beale? He is really great on the bongos and I'm sure he would probably help you with your project for some fried chicken, a slice of watermelon and a cup of goats blood. A good worker too, if maybe slightly lazy at times.