It varies depending on how much charge is in your battery before you start driving and your driving style. On the motorway, it'll take 25-30 minutes to charge the battery. In a town or city, you'll need to double that timeframe. It would make more sense, if you can, to connect a battery conditioner - but this will require mains charging so you'd need a garage with power, or to connect it in the house through a window (with an extension cable) every now and then. The Kuga you mention has start-stop (i-stop), so I'd recommend this charger: amzn.to/3pDDuhB

If you don't have an Amazon account, I believe it's also available at Halfords.