It could be a simple bad connection or a sensor, or the self levelling may be a bit iffy.  The "visit workshop" is because Bentley didn't expect the owner (or chauffeur) to get the spanners out!  You don't say what year, but as it has the fault message I think the selef levelling may be a hydropneumatic system, similar to the Citroen set up, with a pump, fluid and a reservoir.  If so, have you checked the fluid level?  Low fluid sloshing around on a corner can put the warning light on intermittently.

Hope that helps.

Tim