I believe they're Zeniths, 18 x 7.5 ET51.

Pretty sure you'll find the fitments for the Skoda will be similar to the equivalent Golfs, possibly with a little more room in the rear guards again.

Something in the 18 x 8 ET45-48 range would look good and not generally cause any rub issues - you can go up from there but then risk the possibility of scrub depending on your suspension.

Would recommend checking into what some of the Skoda guys have done as I am far from an expert.