Wow im a FTG myself and i cant beleive how your plants look, I was gonna say if your 6 weeks into flower and they are bad then just stick em in darkness for 48 houirs and then harvest,
but to be honest looking at them its not worth doing.

The only thing i would suggest is maybe trim them back a bit (taking off the worse) and stick them under 24 hour cfl light for 4 weeks to try and reveg them.

If moneys short just get some 'multi purpose compost' (anout 1.00gbp-$2 a bag)
some 7/7/7 npk ferts (for after a couple of weeks, and some nice pure bottled water (look on label aim for 6.2ph)

(the picture shows mine vegged under 24/7 3 weeks from clone (now in flower 2 weeks), in the said multi purpose compost, used npk 7/7/7 at veg and 'aqua pura' water, and nothing else--so although not ideal method it does work 100%, you just gotta have love for you plant for it thrive)

I mean thats the only thing you can do..
Good luck