We have a Fabia 2 1.4 diesel estate, with alloys.  However, the full size spare, which was supplied with the car, is steel. Will it require different bolts if it is fitted?

No. Unless the alloys are aftermarket.

Edited 18 December, 201510 yr by Wino

Don't think so. Skoda use bolts with curved face, as opposed to a flat face. Think they're called radial bolts and they will lock on to the bolthole and close up nice and tight.