Given your concerns, I would move them indoors! There's no harm in doing that although nothing will ever beat the light the sun gives - but indoors they'll have light every day whereas the sun doesn't seems to shine everyday in the UK! :-D You will also be able to regulate the temps which is a plus... If you're worried about someone stealing them - get them inside! You've given them a great start by being outdoors, now finish them off inside!
Good luck!