Just chiming in to say that the firmware upgrade has solved my bed crashing problems! Many thanks to @SusisStrolch for providing the K8800 firmware flavor and @Devrope for suggesing
I think it’s still a good idea to calibrate before each print, as that provides a mechanical check before printing (especially before a long print!).
The latest Marlin firmware is much gentler on the build surface during calibration; it seems more accurate, and quieter too.
I don’t know why this is has not been recommended by Velleman or their resellers yet - (if it’s because V2 it’s too new, I understand) but I expect Velleman would fix a lot of new/newbie (cough, myself) K8800 user’s issues instantly if they begin to support and roll out new printers with V2 or higher IMO