Nick,
Like Jo.clarinet, I taught myself and found the internet a great help. Even before I got my first clarinet, I'd read and absorbed pages of info about embouchure. Though that was no substitute for hours of frustrating practise!

The trick there is never to stop experimenting.
Do a search for 'beginners/beginning/clarinet/embouchure... etc
For hand position, I found this guy very useful:
http://raider.muc.edu/~peroneje/tipsforbeginners.htmMy very first book was Abracadabra which has a great collection of easy tunes to play. However, as soon as you make progress it quickly looks a bit childish.
Books I've since found and enjoyed:
Learn as you play clarinet, Peter Wastall
50 classical studies, Pamela Weston N.B. Not strictly for beginners but starts easy and the most interesting and beautiful collection of music.
H. Klose Celebrated method for clarinet. Even the exercises sound like concert pieces!
Some people recommend the Paul Herfurth Teach yourself book. Fine for an absolute beginner, but I find it very dry and old-fashioned. Fortunately, this and the Peter Wastall book often turn up second hand on Ebay.
For a bit of fun:
Easy jazz singles for clarinet, Russell Stokes.
40 Modern studies for solo clarinet, James Rae.
Both start with easy pieces and are great to play.
As Jo said, Leslie Craven has a great reputation and his website used to have sample pages from his book.
The greatest resource of all is undoubtedly the clarinet forum at:
http://www.woodwind.org/clarinet/index.htmlGood luck,
Steve