How do I replace a Nissan Primera '97 Ignition Switch?

My key suddenly failed to turn in my 'R' Reg Nissan Primera SRi ignition - it was jammed. It can't be turned at all. Breakdown service took the thing apart to get me going - basically I now have to put the key in the ignition (to activate the transponder) and manually turn ignition on using a screwdriver! The ignition system is in bits. I guess I need to replace the barrel (presumably using a new key) which is quite cheap second hand, but what else do I need to buy? Is it as simple as getting a new Ignition 'module'...I somehow doubt it!