Are they a 'one fits all' job, or do I need to order a replacement?

For the Fabia they all look the same on the 16" VRS wheel. Just a spline in effect.

I think there are a number of diferrent combinations with the splines being slightly different on each one. Certainly, although my Golf wheel key looks the same as the Skoda key at first glance, they are actually slightly different and not interchangeable.

lost mine, went to the local skoda dealer where they measured or counted the spines so they could re-order one. picked it up a few days later

I do belive that somwhere is the Locking Key Bolt code. On the Boot sticker or in the service book Etc that came with the car. When I put my old occty on OEM alloys the dealer ordered me some bolts from skoda and the key code came with the bolts....Think it's 4 diget

i dont bother with locking bolts anymore not after i seen how easy they are to get off after i lost my key. i took my car to halfords and they took them of straight away without the locking key!