That's what you use when there is absolutely nothing else and you don't care if anyone respects you. Ever. lol
I gather you're in the UK and Bio Bizz soils and nutes are very popular over there. I can't get much locally here in northern Alberta but just on Monday had to go to the big city 2 hours away and scored some nutes, wall mount fan, crab and lobster meal and some myco at a grow store.
At least I can get ProMix HP here as that would cost a lot to get shipped to me.
I know it's still illegal there and up to recently there was no way I would order anything grow related from Amazon or the like. When I went to the city I got cash from the bank to pay for anything like that to not leave a trail. Feels like 50 years of paranoia is much reduced but still there in the background.