Probably the best place to start. Barbara Jones and the Straw Works team probably know more about straw bale building than anyone else in the UK. For updates on projects they are working on it is best to go to their Facebook page
This book, by Barbara Jones, is basically the bible for straw bale building in the UK.
Straw Build are another version of Straw Works – in fact both companies came out of Amazonails, the UK pioneers of straw bale building. I haven’t dealt with them at this point, simply because I discovered Straw Works first.
Useful site based on the experience of building two straw bale houses in east Yorkshire which are also used as holiday lets. These lecture notes, prepared by Carol Atkinson, are especially useful as an overview on straw bale building.
Lots of information here from US based Andrew Morrison. The section with articles is especially useful as a starting point. Being US based the code and regulatory aspects are not so relevant to the UK. Andrew also appears less opposed to the use of concrete than the Straw Works people.
The international Journal of Straw Bale and Natural Building. Also with a link to a free pdf ebook Building with Bales