Fallgold
Raspberry (Autumn Fruiting) in the UK

You don't really 'sow' autumn raspberries from seed, like. What you want are bare-root canes, and you can plant these anytime from November right through to March, before they really start to wake up. Dig a trench about 20cm deep and wide, pop the canes in, making sure the old soil mark is just below the surface, then backfill. Space them about 45-60cm apart, giving them plenty of room to spread out. A bit of well-rotted compost in the bottom of the trench never goes amiss to get them off to a good start.

Once your bare-root canes are in, they'll just get on with it, bless 'em. You'll want to get some sort of support system in place straight away, like wires strung between sturdy posts, or even a simple fence if you've got one. The canes can get quite tall and heavy when they're laden with fruit, so they'll need something to lean on. They're perfectly happy planted directly into the soil on the plot, no need for faffing about with pots for these.