Wellard
Despite what the previous posts may have you think; it's not actually impossible to get a CAA Permit to Fly for an 'Experimental' Helicopter.
The process is clearly defined under BCARs (British Civil Airworthiness Requirments). The problem is that BCARs are very stringent and require a mountain of tests, paperwork and engineering reports; with no gaurantee of success at the end of it.
Most people consider these requirments to be excessively onerous, and unless they have very deep pockets, for all intents and purposes, are practically impossible to acheive.
Unless you have excess cash, stress levels and heartbeats, I'd concurr with everyone else.
JJ