We have a 2015 Troll so the bulbs used on your Troll will be the same as ours.
They are all standard 12-volt car bulbs available from Halfords. The only difference is that the rear indicator bulbs need to be amber-coloured ones and not clear bulbs as the lamp lens is virtually clear.
The front and rear lights are left in the body trim and accessed from the rear of the fitting.
However, the reversing light and rear hazard light have to be removed from the body trim by pushing up a clip at the bottom of the lens and the bulbs are then accessed from the rear of the lamp fitting.
The top side light lenses lever off and use small festoon bulbs.
Hope that helps.
Alan