Having driven a 1.4 tsi mk 23 octy I was quite impressed and am thinking about trading upfrom my 1.9 tdi mk 2. I have a set of winter steel wheels for my MK 2, will these fit the mk 3?

In principle, yes. But most probably will 15" rims NOT fit. What is the wheel dimensions?

PCD (bolt pattern) and ET (offset) should be fine. You haven't mentioned the size, but I'm guessing they are 16"? I'd be surprised if the brakes are bigger on the 1.4TSI than your older 1.9TDI, so they should be fine.

Using my 15" MK2 Octavia steel wheels on my MK3 Octavia 1.6 tdi. Had them on all last winter and going on again next week. Octavia MK3 has 16" wheels as standard but privious one had 15". They have been fine.

Thank you all, not sure about size,  but they are 15 or 16 inch