What are the likely causes for my engine to judder when changing from 1st to 2nd at about 1500 to 2000 rpm over this revs seems to be all right and the engine management light has come on?

The juddering during the shift from 1st to 2nd gear could be caused by several issues, such as a faulty clutch, worn transmission mounts, or engine misfires. The engine management light indicates that the vehicle's onboard diagnostics have detected a problem, which could relate to the ignition system, fuel delivery, or emissions control components. It's advisable to have the vehicle scanned for error codes and inspected by a mechanic to diagnose the specific issue and ensure safe operation.