So sequentially, in other words so just half a dozen seeds at a time each week and sow them individually so you do not have to thin. Just keep doing this week after week...

agree withMG with a slight deviant i would say 2 weeks

Yes that probably works as well… also consider getting a packet of salad leaves seed this is the sort where you pick the outer leaves and let the inner ones keep growing and is what Bulba and I use.

Im going to be sowing about 10 seeds a week....i get through about 2 or 3 icebergs a week in winter so use a lot more in summer.

Thank you all for your comments.
Would this work in summers where temperature in June can go to 30C - 35C although that isn't constant. Low temperature in our summer is about 25C. We have a lot of sun.
I shall try starting, as advised here, but in containers then plant out. Ours go to seed very quickly.
I have been planting thick rows of lettuce.
Thanks again, Clementine

Should still work so long as you keep well watered. The majority of lettuce and salad leaves sold in the UK are grown in Spain.

Bibb is the most heat tolerant variety of lettuce that I know of. We can't keep it all summer here in southern Arizona, but it might work for you, Clementine, since your nights will be colder than ours.

Thank you both for responding.
Interesting to know that the UK imports lettuce from Spain. I believe we import spinach from Japan, can't fathom that one out.
In the winter I buy organically grown kale, broccoli and carrots from America. We root-cellar a lot of stuff. We have our own potatoes from one season to the next, same with apples. Some apples still good from the previous year. Underground root-cellar.
I hope your weather in Arizona is OK now.
Clementine

Kind of warmish, Clementine. It'll be around 21º C today, and may exceed 31º on Saturday. I hate to think what summer will be like this year! :/