Going to seeds

From a couple of punnets of mixed lettuce, purchased last autumn, I have now lettuce growing all over my garden simply because I am not good at thinning and disposing off the extra seedlings that appear when the first lot went to seeds.  Now I am picking beautiful lettuce flowers, some blue, some yellow, to go in a vase.  I tend to pick the lettuce by the leaves, rather than pulling out the whole head, so I am left with so many going to seeds.  The varieties I have growing are, cos, oakleaf and the green and purple mignonette.  With the kind of heat that we are getting today, well over 30 degrees centigrade, I would have to shelter the baby plants and give them plenty of water.  I am beginning to find seedlings as I work in the garden.  Some I will leave where they are but those in ridiculous places would have to be transplanted.  I can't allow the seedlings anywhere near the eggplants, chillies or cucumbers.  They will shoot up and overshadow the slower growing vegetables.  I have found a couple of eggplants, well formed and growing bigger by the day.  I found a cucumber, about 6 cm long, still too small to pick, and it was hidden under the leaves.  If the lettuce seedlings would catch up to the tomatoes and cucumbers, I will not have to go looking for salad ingredients at the market.  All this never ending cycle needs is the assurance of rain.  I hope this last day of 2009 will bring some rain to quench my very thirsty garden.