CW,
Are you eating on the company dime..? I could think of a few high end places to recommend in London to dispell the myth about British food, but you might not want to pay for it yourself..!
Where abouts are you...? Like you said, it's quite a big place, so 'outside of London' covers most of the country..!

Which direction..? Are you still in Greater London (or inside the M25) or are you in another town.