Information online is quite confusing. Multiple part numbers and manufacturers. Does anybody know what was fitted by Skoda originally on these engines?

According to ETKA, it's the first or third 'item 11' depending on whether manual or automatic transmission. https://skoda.7zap.com/en/cz/fabia/fab/2004-225/9/905-905000/

So NGK BKUR 6 ET-10 for manual gearbox, or NGK PZFR5D-1 for automatics. 

Economy versions also available.

It's worth fitting NGK Iridium plugs if you're keeping the car since plug wear kills coil packs and these engines eat plugs.

Thanks guys!