The CAA representative said the GA had 1 fatality per 10,000 hours
Too high. But your sums have gone wrong somewhere anyway.
http://www.caa.co.uk/docs/33/cap780.pdf
The overall reportable accident rate [for for small conventional aeroplanes engaged in non-public transport operations] for the period [1998-2007] is 179.0 per million hours
and the fatal accident rate is 11.7 per million hours.
The fatality rate from the graph in that publication is between 15-20 per million hours.
The fatal accident rate is therefore probably of the order of one fatal accident per 10 million nm, or 1 per 20 million km.
Road Casualties in Great Britain, Main Results: 2007 reports 2714 fatal accidents in 510 billion vehicle km, or about 1 per 200 million km. That's about a factor of 10 less than GA.