ok my fellow brit well i allways start my seedings under 110 wat floros as soon as my true leaves apeared i plased them under 600w hps an a 250w hps in my grow room as for when to flower them it dont mater how old they are just make sure your plant is 12/18 inch tall i have add mutch success this way as for the nutes cant really help you m8 i grow in soil anyways good luck.