On my 2007 caravan I swapped out both the 12V and mains filament bulbs for LED types on the spot light types The 12V D.C ones are bi-pin G4 and the 240V bi pin ones were GU10 bases ( these have thick pins - stepped at the end) . THe number usually represent the distance between the pins.
Take out the bulbs and compare with pictures on the web to select , some are warm white (soft white light) and cool white ( brighter, harder white - with better colour rendition).
For the ceiling lights (12V) I searched " 12v caravan ceiling lights " on the web and found one that was of a similar diameter to the old filament types.
On the kitchen under shelf strip light I kept the housing and ripped out the fluorescent tube and end connectors and driver module and fitted self adhesive cool white strip LEDs , these come as 12V and 24V and can be cut to lengths and little connecter fitted on the end or wires soldered onto the little copper pads. I've attached some images to help you select