What nutes should I use when .....

This is my first grow, I'm growing in pots just with clay pebbles currently using vita link a+b for veg. I'm about to make the transaction to 12 12 on Friday. Just wanted to know what nutes should I use for my next stage. I'm growing 2 Uk cheese and 3 snow white under a 400 mh my grow space is 1.2 x 1.2 x2m will upload pics later. Any help would be much appreciated cheers.

a fert high in P. u still want to give low dose N & K as well, but P should be the main one, any good bloom fert will do.