Cheap multipurpose compost?

Really. For the extra few euros you spend on a decent compost will pay for itself 10x over. Cheap is cheap for a reason mate. Biobizz All mix would be a good additive nutrient rich sub. You really kinda wanna lead with the same brand. As dif ones have dif ph. Yes, it'll all combine in the end. But all mix is cheap, its actually the same price as light mix if I'm not mistaken. I was using it. But, I kept getting gnats in my all mix. (This is more down to the storage of the place where you bought it) it has a high shit content. And stinks. So, if you're using it outdoors I advise to use it not at surface level. As you'll have all creatures coming for a taste.