Cap 804, Flight Crew Licensing: Mandatory Requirements, Policy and Guidance says:
Multi-pilot aircraft
For aeroplanes, it means aeroplanes certificated for operation with a minimum crew of at least two pilots;
For helicopters, airships and powered-lift aircraft, it means the type of aircraft which is required to be operated with a co-pilot as specified in the flight manual or by the air operator certificate or equivalent document.
So my apologies….
The UK Civil Aviation Authorities Information Notice (IN-2013/107) adds:
It can be seen that this definition includes all helicopters for which the Type Certificate specifies a minimum flight crew of 2 pilots, and any other helicopter for which the operating rules applicable to the operation require that the crew comprises a minimum of 2 pilots. Choosing to operate a single pilot helicopter with 2 pilots as a policy of the owner/operator of the helicopter does not make it a multi-pilot operation; as flying the aircraft multi-pilot is not required by the operating rules in such a case.
And it continues:
Requirements applicable to pilots
4.1 Requirements applicable to pilots intending to obtain a Multi-Pilot Type Rating:
i. Where applicable, comply with the prerequisites for the first MPH type. See point FCL.720.H(a) and (b).
ii. Where applicable, comply with the MCC requirement. [MCC/VFR if only for flight in VFR; MCC/IR for flight in IMC/IFR]. See point FCL.735.H.
iii. Complete an approved multi-pilot type rating course for the helicopter type. Complete a ‘full’ course if a single pilot type rating is not held for the type; or complete a single pilot to multi pilot type rating extension course if the single pilot type rating on type is held. See point FCL.725(a) and AMC2 FCL.725(a).
iv. Pass the theoretical knowledge examination for the helicopter type unless the single pilot type rating is already held. See points FCL.725(b)(1) and (d).
v. Pass a multi-pilot skill test on the type. See point FCL.725(c) and Appendix 9 (of Part-FCL).
And that´s VFR only….IFR is another story on top of that..