Many apologies to everyone but I am still a bit cornfuzed (normal for me actually)
The place where all my seedlings are located is a very large window in my kitchen it gets light all day long, indirect light in the morning direct sunlight for most the afternoon.
I have tried moving them toward the back door to the garden (which is a glass door) and still then end up taller rather than fatter. This happened to my herbs which grew very tall and didn't survive.
My peppers didn't get so much light and they seem to be growing slowly outside in the cold frame now.
Could it possibly be that they need less light??? And are growing too fast? Or perhaps I am letting them stay too long in their wee pots and they need to go outside sooner?
I will try planting the carrots direct, I am going to use a large planter rather than in the veg garden to protect them from carrot fly and so the slug meanies don't bother the sweet wee things.
Will try a few cabbages in the same way then transplant them.
The sweet peas are coming along nicely in the same window...I'm sure you all will have more suggestions. Thank you very much for your kind suggestions so far!!

Gardens are like people, they need love, warmth, food and care, and always are their best when shared with others!