When you die, perhaps you should get your family to put your ashes in a salt cellar attached to the bumper of a car and scatter you the entire length of the A303.
Saw the programme and quite enjoyed it. There's an infinite amount of material there as you could make programmes about every one of Britain's major trunk roads. The A56 is my particular pet road as much of my recent life has taken place up and down its length.
This map explains British road numbering and will interest a few on here. Roads are numbered according to their zone, going clockwise:
For example Cheshire and Cumbria have roads numbered A5* and B5***