Just to conclude my ramblings. Set up drivers, as per advise and the excellent video, which used a breadboard, and then connected a bench power supply, giving me 30 volts. All run excellently now.
Another success was to adjust the travel in grbl to suit my lead screws so that when I jog 10mm I get 10mm movement. A bit daunting at first but so simple and over the moon with the results.
No bad for a 70+ beginner, enjoy.
Thanks again for all the help