radio 'SAFE' mode - is it always just a simple case of re-entering the code?

Look in the Radio's Handbook, it explains how to enter the code, which should be printed on the inside of the front cover flap.

It's worth stashing the code on your mobile phone so you won't be stranded without any music on the way home from the garage if they disconnected the battery to service your car ;)

Cheers,

Mark.