how to change a ignition barrel for corsa?

Hello,
I have recently some how managed to break the barrel on my 98 corsa diesel 1.7 an in doing so the barrel came out when taking the key out, I have been advised to change the barrel and key.
Now I have not touched any of the screws or casing to get to the barrel normally, a realise this and I have read other hints on how to replace it but all start by removing it normally.
there is no damage but I was wondering if I brought a barrel an key an jus replaced it, is it as simple as slotting it into place or what, and do I have to buy a special one for my 98 corsa or can I get any barrel for a corsa or does it have to be specific to my LS model (lol I know sounds stupid but can anyone help)
Thank you

sam
October 2009