White widow auto outdoor uk south

Hey guys this is my first grow! I’m using a feminised white widow auto flower by dinafem. I germinated using the paper towel method. I brought 4 blocks of coco coir which in total amount to 40 litres when mixed with a total of 40 litres of water, I also added some multi purpose feed at an 1/8 of the recommended dosage as the coco coir had absolutely no nutes like you would expect to find in a soil medium. I adjusted the ph to 6.5 and let the coco coir soak overnight. The next day transferred the coco into a 40 litre felt pot and planted the seed so it was just covered over. I’ve been feeding with just pure water at a ph between 5.5-6.5 but today (day 4) I added the amount of a tear drop to 1.5 litres of water again ph around 6.5, maybe it was a bad idea I suppose time will tell! Any advance from outdoor growers around London would be appreciated! I’m really intrigued to know what sort of yield to expect from this strain. At a guess I was thinking around an 0z but If I'm honest I would like 3 times that! Thanks in advance