Everyone's experience will be different. Having owned and driven EVs for more than 5 years I would say that the 30% drop in range between good summer and poor winter conditions is a reasonable estimate for a single long journey.
Things will be lots worse for lots of short journeys where the car has to be defrosted and brought up to a comfortable temperature repeatably.
If it was extremely cold you could use 2kWh of energy each day just warming your car and battery, which is 10kWh in a week or 20% of your battery for a SR before you even turn the wheels.
The good news is, come spring the range will creep back up again.
For many people the range of the car, even in winter is more than enough for their regular daily need, so provided you can conveniently recharge each day this isn't a major issue. If you haven't got home charging, or regularly drive much more than 50% of the WLTP range of your car in a day then it will be more of a struggle.