Arduino connected to a snow cannon - relay?

I am new using the arduino to control a mains powered device. The arduino will be connected to the on/off switch for the device, which happens to be a snow cannon from maplins.

I obviously need a relay to complete this, the device is mains powered AC 240V/4A. Looking for advice on relay to use, is suitable?

Also, if there is any other advice you can give as to set it up and not kill myself, it would much appreciated, especially to protect the board!

I would avoid that one. If you want to switch 4A you are best getting at least double the rating. So go for a 10A one. The 10A version will not switch at mains voltage so go for a bigger one. Best is not to go for a subminiature relay as they are more challenging to wire up with mains bt go for a bigger one. Hint - make sure everything is mechanically solid and doesn't move when wiring up mains.

Jameco has a 40 Amp 280VAC solid-state relay for $19.95

KD20C40AX - Jameco part number 176719

What do you mean by the 10A will not switch at mains voltage. I found this one and the sales guy said it would be okay -

Cheers for the advice guys!

What do you mean by the 10A will not switch at mains voltage.

The data sheet on the link you posted first said the voltage rating of the contacts for the 10A version was 120V AC.

That new link looks fine.

Thanks. Looking forward to this project, great community here also, one of the most repsonsive I've seen, thanks for the info!