I recently did a major service:
Valley pan
Valve cover gaskets
Spark plugs
Water Pump
Thermostat

Now my engine rattles like a diesel on start up and when i drive but is fine when it idles

Im hoping its not the Vanos, it wasnt making that noise prior to me tearing the car apart. Could I have the belt on too tight, after replacing the water pump. I adjusted the belts tension back to the same points, which felt pretty tight.