We have training companies covering WPF with the content targeted firmly at Developers. UK based Ian Griffiths is delivering 4 day training courses for Pluralsight and we have skilled up UK trainers in http://www.xpertise.co.uk and http://www.pygmalion.com to help with our early adoption work in the UK. We also are just working out details of a public (and likely free) 3 day Vista/.NET Framework Course which will include a day or so on WPF.
However - I was asked about training resources on WPF for Designers. WPF for designers really means (to me anyway) training on Expression Interactive Designer (EID). Unfortunately I am not aware of any folks in the UK offering training specifically on EID (please let me know if you are!). The good news is the product team commissioned training videos which are now online and a good place to start. Check out
The Expression team also tend to signpost tutorials and articles at http://blogs.msdn.com/expression/