Any recommendations for someone to insulate our roof?

In the light of the burning globe/ escalating fuel bills, we're looking for someone who might insulate our attic roof. We want to insulate directly under the roofing tiles/felt, as opposed to the attic floor, which we've already done.

Has anyone had work like that done before? Could they recommend anyone who works locally? Ideally it would be an insulation specialist. Any thoughts would be much appreciated, and thanks very much.