I bought some auto ak-47 seeds about 3 months ago, with the intention of growing them in my parents greenhouse. However, after doing a lot of research I reached the conclusion that auto flower plants achieve their full potential more often inside. The main reason I see for this is that inside you have the power to give the plants 20 hours of fully intense light every day - with auto's, in general, it seems that more light = bigger plants and higher yields. That isnt to say that growing outside is a waste of time, there are some amazing auto flowers in this thread that have been grown outside, but I would guess that in these circumstances all other conditions were perfect (not sure how likely this is here in England, we've had a stunning 3 weeks - how often do our summers stay like that?). What light have you got them under indoors? Because my suggestion would be to put them outside on the good days, and keep them inside under your lights on the bad/rainy days (but only if the intensity of light you have indoors is sufficient). I would also consider moving them inside under your lights when it gets dark outside, so as to insure that they get 20 hours of light every day, and therefore 4 hours of dark. What size pots do you have them in? Because pot size also has an affect on how well your plants will grow, if they're in small pots then make sure you let them dry out between waterings (this will make the roots search out the pot more quickly) and be ready to transfer into a pot of at least 2 gallons as soon as they are ready.
Whatever happens, I hope your grow goes well, always good to see new English growers. Im still a noob myself, so dont want to act like im an expert, but ive done lots of research and am more than happy to share what ive learnt, so feel free to ask away.
Cheers
B