Posted: 28/03/2013 at 07:39
Sweet peas are hardy but will need hardening off gradually if you've started them in the warmth of indoors - there are a lot of threads on here giving sound advice about growing sweet peas - use the search facility in the top right corner I think you could treat your violas the same way.
Keep your tomatoes indoors! They can't go out for ages yet - keep potting them on as they grow and keep them in as much light as you can to avoid them growing too leggy in search of light. If they do get leggy you can plant them a bit deeper when you pot them on as the stem will grow some roots. There are also lots of threads about tomatoes - again use the search facility to find what you need
I must admit I've not started any of my seeds off yet - I'm going to start my toms this weekend as I only have little cold growhouses too.
Your lettuces might cope with being moved outside if you harden them off gradually, putting them outside in the sun for a little while then back indoors, increasing the time they spend outside each day until you think they can cope with it - it does depend on the variety - some are hardier than others.
This is a very unusual spring, and you might have to start again with some of your seeds if you run out of room for them indoors. Such are the joys of gardening - welcome to the club
I'm sure there'll be lots of advice and encouragement from others later on today ....