Had the head cover off to put new glow plugs in  the cover wasn’t put on correctly and it’s dumped all the oil. all back on properly but won’t start the plug lights still on anyone know what it might be or what to do 

There is likely to be a connector plug on the electrical circuit that has pulled loose or even completely apart.

I hope it’s something simple will I need to take the glow plugs out again?

I don't know, I have never done the job. Go round the engine and check all the connectors that may have been disturbed or strained when you took the plugs out. If that doesn't resolve the problem I can only suggest to consult a car electrician.

Okay mate thank you