As part of the planned safety evenings research I've gone through every accident report involving a UK helicopter that I can find since 01 Jan 2000, mainly these are AAIB reports but some are from foreign investigation bodies.
The primary cause of UK registered accidents is mishandling / loss of control in the hover causing heavy landings and / or tail rotor strikes usually followed by some sort of rollover. Most cases involved a training sortie of some kind some dual, some solo, figures on those will follow shortly.
The primary cause of UK registered fatal accidents is Loss of Control in IMC.
The figures are here
http://www.helicoptersafety.org.uk/commonaccidents.asp.
The figures will be expanded slightly later this week to show in more detail what I state about accident causes.
I plan to go further back through the accident reports if time ever permits.