I've forgotten my Ipad's four digit security code. I've tried 2 codes but I am worried about a third attempt in case I get it wrong and the ipad 'self destructs',. Help please!

With respect , how does anybody know whether it's been nicked or whatever ?

connecting it to itunes on the pc/laptop it syncs with will allow you to reset it.

If you can't remember the code you'll need to wipe the iPad and set it up again. If you've backed up either to iCloud or to a computer then you'll be able to restore your settings and data after wiping it.

If you've previously synced your iPad to a computer then you will be able to perform a backup without needing the passcode on that computer.

More information here: http://support.apple.com/kb/ht1212