I have been using Kauni Yarn quite a bit recently for various projects – some of which you should be able to see (and knit!) by the end of the summer or early Autumn.
Based in Denmark (using Estonian wool), Kauni has an ‘environmental attitude’, encouraging recycling and the use of environmentally friendly dyes. The appeal of their yarn, and the single colour 8/2 in particular, is that it is 100% pure wool, softens and felts slightly when washed and is available in a jewel like array of colours – from delicate, blush pinks to deep reddish browns, and the brightest of spring, leaf greens to the softest smoke blues. I used it for the Tweetie Bird pattern and you may be able to buy it in the UK from here.
Katvig is another interesting Danish company – they have been making gorgeous, sustainable children’s clothes since 2003.