UPDATE: It's fixed!

I've just been the garage and they plugged it in their machine and checked it out. The hardware side of things is all good... air bags etc. but the control unit and/or sensors is what threw the fault up.

He cleared the faults, re-programmed it to reset the ride height and it's back to normal. I've been over a load of bumps since, hard cornering etc and everything is normal.

From what the mechanic said, chances are it's the main control module.

Once again, I'm so glad I have my warranty!

Thanks everyone for your help.