Thanks for the prompt answers, comments & advice. Good to see that people on the Briskoda forum are just as helpful as when I left 3-1/2 years ago after I sold my 2012 Octavia vRS..
I don't intend to change the tyres that are on the car until they are worn to an extent that needs a change. The car is actually a 2019 reg (first registered 31/5/2019). Tyres are currently Kumho Ecsta 51 (forgotten the letters before the 51!).
As suggested I will evaluate what the car is like on the current tyres before deciding whether to change size when a change becomes necessary (insurance company may have a view on a different tyre size being fitted). My wife's current car, a 2010 Clio 1.2TCE (100) is on 195/50-16 tyres which I have always thought were bigger than the car needed (bigger tyres than previous Cavalier SRi & Sierra XR4x4 had fitted!).