i went to a bnq megalopolis, and they had sweet fuck all in terms of choice for soil. didn't have what i wanted at all.
a friend who's been in green for the alst 20 years or so reccomended John Illes no.2 mix. along with perlite and 5mm sand, in like a 3:2:1 ratio. i used this and it seemed to give pretty good results. was my first grow so i can't comment on just how effective it is, but certainly ran into no drainage bug problems blah blah and the plants seemed to like it. i had to goto a propper garden center to find what i was after. even the flower pot range at bnq is pretty limited, and very expensive. i just shelled out £3 a go for run of the mill plastic runoff tray things...