Thanks lads. I received similar advice elsewhere about the heater and fan at night for mould so I will definitely put them in place.

No photos right now as I don't have a digital camera. Which is a pity, because the fan leaves have been yellowing for some time now and I don't know why. I'm certain it's not insects or a lack of water, though it could be a lack of nutrients. However, I've also read that yellowing can start to occur naturally in the flowering stage, and my plants have been in that stage for about three weeks now. Any thoughts?

The pistils continue to sprout up but there's no sign of the buds to emerge and begin to resemble the ones you see in photos of harvests. I'm kinda expecting my buds to be smaller, due to the far from ideal conditions for growing and also due to the possible disease/nutrient deficiency I mentioned earlier. Will let you know how things progress in the coming weeks. Thanks again.