hey white widowmaker i think its defo worth buying feminised seeds especially at £35, i paid £40 for mine i spent the same on 20 unfeminised seeds and ended up with 1 female which was really shit you dont want males they will pollinate females if they are in the same room as the pollen is spread from plant to plant in the air circulation (wind)
the plants arnt asexual they are either male or female although you may get mutations which can make the plants both sexes doesnt happen a lot tho this is called a hermaphrodite
i grow mine in a small clothes wardrobe probably about 1metre in lentgh across and bout 2m in height its not very wide tho i can get 10 plants in there comfortably
its up to u if u get feminised but id rather spend that lil extra to garuntee they are all females
people say that the sex is genetic and cant be changed i feel this isnt true as if the plants get a deffiency or too much of something or stressed jus before you flower they is more chance they will be male
oh and if you leave males in there and they pollinate the females youl jus be left with a fuck loada seeds and no bud
throw away any males you get asap unless u want to get seeds to grow more plants