Looking for a set of wheels for winter tyres, car is an Octavia 11, 1.6FSI, 07reg. Markings on the wheel are 6.5Jx15, ET50 but no sign of PCD. Am led to believe its 5x112, is this correct?

Correct

Try these that I found on Ebay: VW TRANSPORTER STEEL WHEELS 6X16 FOR T4 AN CADDY 5X112.

I've been told that they will be ok to use, as I was thinking about getting some Winter Tyres in the next couple of months for next winter.

if you have 15" wheels I'd run those for winter as you can run chains on them and I'd look for a set of 15 or 16" wheels for summer tyres.