changed clutch and now not starting

[Niall]

Not sure if the 1.8 is the same but the 2 earths on top of the gearbox tight?

this was the next thing i was going to suggest

Also, the crank shaft sensor is on top of the gearbox directly under the thermostat housing with a wire coming off of it about 10cm long with a brown plug on the end of it. If its not plugged in, it wont start.