You could try - Dawkes Music. Maidenhead; John Packer, Taunton; John Myatt, Hitchin; Ackerman Music - various shops in S of England; Dean Pelling, Bexhill; Howarth, London; ......
That's just for starters without really thinking about it - many shops sell Yamaha instruments.
Good luck in your hunt.
Ian
Re: Yamaha Clarinet YCL-450 16:37 on Friday, August 28, 2009
I bought my 450 used, which is about 5 years old. I'm using it as a back up clarinet/to play in school and outside. I bought it for about $300 used and have had a fair amount of work done on it. I think it is definitely a good clarinet for the price I paid. Its a good idea to buy a 450 rather than a 250 because the price difference is only about 200$. Good luck finding a clarinet =]