We sell 3000mm solid oak worktops on our website.
Take a look:
http://blueprintjoinery.co.uk/products/Tuscan-Solid-Wood-Worktop-European-Oak-40mm-Thick.html
If you're interested give us a call on 01691 671020
Kev
I agree about not using MDF, even treated it will become a problem over time. I think even PVC will look a bit naf.
For a good finish I would recommend using a softwood timber such as pine and then using an outdoor stain preservative. A much nicer finish than either MDF or PVC.
Kev