I'm no expert but...
Have you looked at the videos of Andrew Pyrah on YouTube? He grew Royal Haze from Royal Queen Seeds (feminized and autoflowering seeds) on a windowsill in Amsterdam with no artificial light or heat and the plants came out well. From 2 plants and with minimal effort he got a yield of 15 grams (dry). That's not a huge yield but you can't have it all, right? Take a look at his videos and see what you think.
From what I know of auto-flowering plants, they stay on anywhere from 16-20 hours of light? right the way to harvest. A good idea for a summer grow when relying on natural light but will struggle now that winter is approaching. Unless you don't mind supplementing the light when the natural daylight hours are to short. Having said all that, my knowledge of autoflowering strains is limited, there could well be strains that only require 12 hours of light in the flowering period. You will still be up against the natural light being of low or not enough intensity to support good flower development during winter months.
I would suggest growing in either canna terra pro + (soil) with canna terra 1 part nutrient or canna coco with canna coco specific nutrient. Both very easy to source in the uk and very easy to work with. Just use 11 litre pots and a tray to catch the run off when you water (aim for 15-25% run-off when watering and don't let the plants stand in water. Let soil/coco dry a little between feeds). Don't expect miracles if not using lights indoors. If they are not performing it will be the lack of light and environmental issues that are the problem. Don't be persuaded into buying expensive supplements from the hydro shop. With not enough light the plants will not benefit and in some cases will make problems worse. As the plants will not be using their nutrients as efficiently as a plant under high intensity sunlight or hps lights, feed under the stated dose to avoid overfeed.
Take note of the post that mentions managing the smell. The smell will fill the house and beyond if unmanaged.