Vauxhall Astra H - juddery astra - gvmllr001

hi all just want some opinions please. bought a 2004 1.6 vauxhall astra twinport. when driving the car,upto 50 mph the car has a little judder.after 50mph the car runs great. the car starts first time and idles normal. the engine management light is on(continous). could my car have a faulty coilpack...any help appreciated. thanks.