i don't really know how to use blender
use a real river then, To be honest i don't get why you dont want to use a real river. If its easier and will look better the vfx why not use it. And if your in some place that doesnt have rivers, for example a desert, you can try to use a hose to make your own mini river then you can composite it to where you want the river
There are many great resources on it....I'm not great at 3D/Blender at all (I can hardly model tbh), but when you look up the relevant tutorials you should be able to make something. I did something similar for my music video. In this case an ocean rather than a river, but same principle. I basically set up a plane in Blender, applied an ocean modifier, tweaked the parameters. and saved it as an "animated" OBJ file (ensuring it can loop). This I then imported into Element 3D in AE (but I believe you can use animated OBJs in Hitfilm too?), and presto.For the example (towards the end of the video):http://www.youtube.com/watch?v=hZKss9RBOs4But as per some of the other folks, nothing beats the real thing if you want to go for realism!
Vue is paid and it's not a fluid simulator. He would be better of in blender or better yet using a real river