I have a Fabia 5J with 1.2 77 TSI engine. (CBZB)

Plug leads don't seem to last well - last 4 services it had new plugs and leads 4 years ago, again at 3 years ago with new coil pack as well, then last two services not replaced (but new timing chain a year ago) and all OK at last service, just a basic oil change and check over. A couple of weeks since the last service, it is now missing badly when accelerating uphill - brought on engine light, EPC and tyre pressure lights. I have a Ancel VD700 scanner and it shows codes for misfire on cylinder 3 and shutdown of cylinder 3.

The mechanic who services it, an independent Euro car specialist who I think is great, is booked up for 6 weeks and snowed under, no hope of seeing it earlier. So I want to change plugs and leads myself. (I'm pretty competent under the bonnet.)

I have read elsewhere online that if the plug leads are copper core, then I should stick to Bosch spark plugs (FR6H1332) but if they are resistive leads I should use NGK plugs IZFR6P7. I've got my doubts about that, as looking at suppliers online, it appears the NGK branded plug leads are copper core...

Currently I have Bosch plugs and BBT branded plug leads (copper core.) Getting another set of the BBT leads, open to sugestions on which plug to buy...

And is any other fault likely to cause this issue?