advice for stickleback pond uk

im making a 4th pond for my garden as i currently have a frog pond a newt pond and an ornamental fish pond , now all that is left is a natural fish pond , the size is 1.5m x 2.5m width and length and 1m deep , so around 1000L i think , i was planning to stock with three spined stickleback as they are native to the uk and dont need feeding much (i dont think) and i will heavily stock the pond with plants. i need advice on whether they can be kept with other fish like minnows , how many to get (i was thinking 2-3 males and 7 females) , what native uk plants to get , whether to get a small filter to stop it going stagnant , and any other general advice on how to care for them and make sure they are happy (also is this allowed as its not really a wildlife pond even though its meant to be similar to a wildlife pond)