I am the definitive answer
Manual link is
here
Class I is any motorcycle with or without a sidecar upto 200cc
Class II is any motorcycle without or without a sidecar (and automatically includes class I)
Class III are three wheelers upto a maximum of 450kg unladen weight
Class IV is a huge class, Cars, motorhomes, dual purpose ie pickups (for now - will change this year), minibuses with 9-12 seats, goods vehicles upto 3000kg dgw, ambulances and a few others
class V is a private bus with 13 or more passenger seats
Class VI is a proper PSV bus (only testable at VOSA test stations)
Class VII is a goods vehicle over 3000kg upto 3500kg dgw
Allantheboss:
If you were to remove all the lights off yuour bike it would be perfectly legal provided you olnly rode it during the day and not at times of reduced visibility, certainly not needed for test