I wanted to recommend this company as I saw them at a local show this year and although I am tempted to keep them a secret I felt really I should share (I'm not connected with them at all by the way).
The website is www.rebekahsveg.talktalk.net
You need to email them from the site for a list.
The seeds were about £1 a pack (or 6 for £5) and they had a huge range of unusual stuff. The chap was really helpful to, really knew his plants! We were buying some salad leaf seeds and he said "This is a grat one, try some" and produced a plant pot and encouraged the kids to pull off a leaf. They loved it and it tasted great to.
I don't think they are organic seeds but they look lovely in their simple old fashioned brown paper packets and they are great value. Just thought I'd share....