Yeah you can get it from most supermarkets lol.
I use bio bizz organic bloom juice for flowering. When I put my plants on 12 12 i mix some sulphate of potash and some super phosphorous in some soil. Then transplant the plants that are going onto 12 12 in there final large pot with the soil i just mixed with the p and k. Then when feeding them on flowering i use the bloom juice a bit of organic liquid seaweed and molasses.
Yes using mollasses helps but the wieght on them buds. For the price that it is you got to use it. A lot of people only use in on the last two weeks of flowering but i use from the beginning just put a tiny bit of it in some boiled water. Let it dissolve and cool then u can feed to ur plants.
You can pick up the super phosphorous and sulphate of potash at all diy garden stores. Wilkinsons do them i know that.
Evil