A key would be to start out with bar and then 40kg trying to do a full snatch properly. You need to take the attitude "Who cares if I miss". Just try to get used to catching a snatch low. When that happens then you can start progressing to heavier weights in the full squat snatch. Try to avoid power work until you have the full lift down.
Try some overhead squats.
Try some drop snatches.
A key would be to start out with bar and then 40kg trying to do a full snatch properly.