We bought oak block worktops from Barncrest at a very reasonable price and they look great. They did have a sale on but worth a look.
If you've not had wood worktops before, be prepared for them to look less than pristine quite quickly, especially if you aren't the most careful cook (or in my case, kitchen porter). Dan's granite worktop is beautiful and pretty much undamageable but my oak already has some marks. These woudl sand out, but I don't mind about them. It's tha patina of age