Sorted - the limit switches for each side of the Y axis did not match the drivers, so when one switch triggered it stopped the opposing side motor. Fine while I was testing limits, not so much for homing operations!
Homing all working now. Just waiting on some ER20 collets now and hoping to make first cuts very soon.
So far I just have a ply bed as I figure I'll probably have a few accidents, then thinking to use an MDF bed with threaded inserts fitted from underneath every X cm to allow fixing from above without using screws.
Need some practice before going for a more expensive material for the bed!
Still overwhelmed by the amount of settings in CAM around ramp speeds, lead in speed, plunge speeds, feed's etc and how much is OK to leave at default and how much to change.