Posted: 13/12/2015 at 11:17
Although it's tempting I'd leave off sowing at this time of year particulary if you are thinking of starting things off indoors. There's not enough light and yes one packet of seeds can produce a lot of plants!
I would imagine those packets that say sow now or in Jan mean indoor sowing or heated greenhouse. A few years ago I had great success with snapdragons sown in Jan/Feb started indoors and then moved out side. I think the secret of their success was that the winter that year was so mild with plenty of sunshine.
I have a few coldframes or sturdy plastic greenhouses which are great for protecting small plants against the worst of the weather.