Leggy lettuce seedlings

[Primrose]

Some small lettuce seedlings sown on my window ledge a few days ago are already sprouting and looking as if they're going to grow too leggy.
I've slipped the tray horizontally inside a cut-off 5 litre mineral water bottle and put it outdoors in the hope more natural daylight light will check them but can anybody offer any better way of keeping them healthy as it's obvious too cold to plant them out yet and my veggie patch is still sodden.
Perhaps I was just too enthusiastic with my sowing dates.

[oldherbaceous]

Dear Primrose, if you don't have a greenhouse i would say you are doing exactly the right thing.
I think lots of people are sowing stuff a lot earlier now, now the winters are getting milder.

[sue-the-recycler]

All my lettuce and salad leaves are in seed trays with the clear plastic 'propogator' covers and then I put them in one of these polythene mini greenhouses and they are doing fine with their cheap 'double glazing' and no added heat.