I am first time to and blogging here there are already good organic mixes on this site and there are also very good cheap organic fertilizers - I use liquid ones which are also good for foliar feeding - I personally think that naturally the thousands of things needed for good weed are in a nice complex organic soils that ideally has a small amount of perlite and vermiculite thereby adding in the positive of hydro without going hydro and without losing the soil complexity necessary to create a complex weed.
peat vermiculite perlite worm castings, guano, coconut hair, coconut chips, dog hair, cat hair, small pieces of dried marijuana stalks left over from old plants and so on
I also use many other things but it largely depends on where you are and what is convenient, by being creative you can create a very complex soil, try to keep the hydro elements like perlite, vermiculite and sand low and the other organic ingredients in higher amounts to create a very rich and complex soil. Maybe you live near a river with nice alluvium or a forest with nice peat, I cook or nuke these in batches to kill creepy crawlies of course before using, you can be creative but must try to make your soil from quality ingredients. I see you are in the UK so you could add a little lovely sphagnum moss to your organic soil and wonderful deep bog peat that is extremely nutritional, just have to avoid the chalk and fir needles if you grow weed though as they prefer a very slightly acid soil.
I have grown alot of hydro vegetables such as tomatoes and aubergines and this was for mass commerical markets in non-season and quite honestly it was nice business but it is not as good as real organic veg for personal exotic consumption, put it this way to make wine from hydroponically grown grape vines would be sacrilige then for me if I want the most premo in flavorful complexity in weed the same must apply so you are making an excellent choice and I look forward to seeing pictures here. Whatever organic liquid fertilizer you use start of 10 times milder than the recommended dosage and very slowly build it up over the weeks as they do not need much as they have good soil and the very mild nutrient is good foliar spray that will not burn