Lettuce is great plant to grow in Britain - it loves our moist climate and will carry on growing through moderate frosts that will come at the end of the season.
Lollo Rosso is ideal for patios and roof terraces because you can just pick off individual outer leaves as you want them - for up to 3 months at a stretch.
Time from seed to plate: 10 weeks
You need a grow bed to produce a significant amount of lettuce. Fill it with multipurpose compost and make a shallow groove parallel to one side where you're going to sow the seeds. It needs to be about 1cm deep. Sprinkle the seed into the groove, about one every 2cm and cover with a thin layer of soil. Water well and label.
Once the seedlings are growing start thinning out the smaller ones to create gaps of 20cm or so between plants. Your plants won't mature properly otherwise.
Sprinkle on some slug pellets if you suspect some are getting nibbled.
Your two options: Harvest the whole plant, or twist off individual leaves from the outside, while the plant carries on growing from the centre - creating a mini lettuce tree! - with a continuous supply of leaves for the table. The latter is probably a better bet because you've only got a few plants. Soak the leaves in water for 5 minutes before you eat for maximum crunch.