I wouldn't be too concerned. They probably won't produce OZs, but they'll prob do alright. I am in NorCal, on the coast... very similar weather (foggy/cloudy/cold)... and though I've been growing indoors (using cfls for light) it's in a garage and the temp/humidity are the same as ambient (50s-60s)... I vegged or six weeks and am flowering for six (in 4th now) and plants are doing well... I also LSTd and topped early... plants are around 16" wide and 24" tall, with 6-8 tops each, in 3 gal pots... I just chopped the smallest plant (about half the size of the others) early and got about 3/8s of an OZ dry. The rest look to be carrying twice that right now.
So long as you have a clear spot where they get sun all day, you are basically looking at about 8 weeks veg time before the nights get longer an your photos go to flower... I would consider a hoop house or other covering to keep temps up depending on your particular environment... and keep your expectations low. Better than no bud at all though, or paying or it
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As for your light leak... wouldn't worry about that either... in veg it's not important at all... in flower... well they're really not THAT sensitive... consider the full moon... preventing light leaks during the dark period absolutely improves growth, but having a bit of light here and there, or occasionally, will not prevent flowering... so long as it's not intense light... if you do a hoop house or something you could always use a tarp or other material to cover them at night once they go into flower.
I stressed the heck out of my plants due to my environment and not having a real grow space... and I did find one very immature seed in the stuff I got from the one plant... but since I am not seeing any actual hermies, I think it was just a fluke.